Repository: bids-standard/pybids

Issue:
Update versionner 0.18 → 0.20?
Would that be acceptable. My initial intent was to fix typos in `versioneer.py`.


Discussion:

Resolving patch:
diff --git a/bids/__init__.py b/bids/__init__.py
--- a/bids/__init__.py
+++ b/bids/__init__.py
@@ -23,7 +23,5 @@
 
 del due, Doi
 
-from ._version import get_versions
-
-__version__ = get_versions()['version']
-del get_versions
+from . import _version
+__version__ = _version.get_versions()['version']
diff --git a/bids/_version.py b/bids/_version.py
--- a/bids/_version.py
+++ b/bids/_version.py
@@ -6,7 +6,7 @@
 # that just contains the computed version number.
 
 # This file is released into the public domain. Generated by
-# versioneer-0.18 (https://github.com/warner/python-versioneer)
+# versioneer-0.20 (https://github.com/python-versioneer/python-versioneer)
 
 """Git implementation of _version.py."""
 
@@ -30,7 +30,7 @@ def get_keywords():
     return keywords
 
 
-class VersioneerConfig:
+class VersioneerConfig:  # pylint: disable=too-few-public-methods
     """Container for Versioneer configuration parameters."""
 
 
@@ -57,7 +57,7 @@ class NotThisMethod(Exception):
 
 
 def register_vcs_handler(vcs, method):  # decorator
-    """Decorator to mark a method as the handler for a particular VCS."""
+    """Create decorator to mark a method as the handler of a VCS."""
     def decorate(f):
         """Store f in HANDLERS[vcs][method]."""
         if vcs not in HANDLERS:
@@ -67,19 +67,20 @@ def decorate(f):
     return decorate
 
 
+# pylint:disable=too-many-arguments,consider-using-with # noqa
 def run_command(commands, args, cwd=None, verbose=False, hide_stderr=False,
                 env=None):
     """Call the given command(s)."""
     assert isinstance(commands, list)
-    p = None
-    for c in commands:
+    process = None
+    for command in commands:
         try:
-            dispcmd = str([c] + args)
+            dispcmd = str([command] + args)
             # remember shell=False, so use git.cmd on windows, not just git
-            p = subprocess.Popen([c] + args, cwd=cwd, env=env,
-                                 stdout=subprocess.PIPE,
-                                 stderr=(subprocess.PIPE if hide_stderr
-                                         else None))
+            process = subprocess.Popen([command] + args, cwd=cwd, env=env,
+                                       stdout=subprocess.PIPE,
+                                       stderr=(subprocess.PIPE if hide_stderr
+                                               else None))
             break
         except EnvironmentError:
             e = sys.exc_info()[1]
@@ -93,15 +94,13 @@ def run_command(commands, args, cwd=None, verbose=False, hide_stderr=False,
         if verbose:
             print("unable to find command, tried %s" % (commands,))
         return None, None
-    stdout = p.communicate()[0].strip()
-    if sys.version_info[0] >= 3:
-        stdout = stdout.decode()
-    if p.returncode != 0:
+    stdout = process.communicate()[0].strip().decode()
+    if process.returncode != 0:
         if verbose:
             print("unable to run %s (error)" % dispcmd)
             print("stdout was %s" % stdout)
-        return None, p.returncode
-    return stdout, p.returncode
+        return None, process.returncode
+    return stdout, process.returncode
 
 
 def versions_from_parentdir(parentdir_prefix, root, verbose):
@@ -113,15 +112,14 @@ def versions_from_parentdir(parentdir_prefix, root, verbose):
     """
     rootdirs = []
 
-    for i in range(3):
+    for _ in range(3):
         dirname = os.path.basename(root)
         if dirname.startswith(parentdir_prefix):
             return {"version": dirname[len(parentdir_prefix):],
                     "full-revisionid": None,
                     "dirty": False, "error": None, "date": None}
-        else:
-            rootdirs.append(root)
-            root = os.path.dirname(root)  # up a level
+        rootdirs.append(root)
+        root = os.path.dirname(root)  # up a level
 
     if verbose:
         print("Tried directories %s but none started with prefix %s" %
@@ -138,21 +136,20 @@ def git_get_keywords(versionfile_abs):
     # _version.py.
     keywords = {}
     try:
-        f = open(versionfile_abs, "r")
-        for line in f.readlines():
-            if line.strip().startswith("git_refnames ="):
-                mo = re.search(r'=\s*"(.*)"', line)
-                if mo:
-                    keywords["refnames"] = mo.group(1)
-            if line.strip().startswith("git_full ="):
-                mo = re.search(r'=\s*"(.*)"', line)
-                if mo:
-                    keywords["full"] = mo.group(1)
-            if line.strip().startswith("git_date ="):
-                mo = re.search(r'=\s*"(.*)"', line)
-                if mo:
-                    keywords["date"] = mo.group(1)
-        f.close()
+        with open(versionfile_abs, "r") as fobj:
+            for line in fobj:
+                if line.strip().startswith("git_refnames ="):
+                    mo = re.search(r'=\s*"(.*)"', line)
+                    if mo:
+                        keywords["refnames"] = mo.group(1)
+                if line.strip().startswith("git_full ="):
+                    mo = re.search(r'=\s*"(.*)"', line)
+                    if mo:
+                        keywords["full"] = mo.group(1)
+                if line.strip().startswith("git_date ="):
+                    mo = re.search(r'=\s*"(.*)"', line)
+                    if mo:
+                        keywords["date"] = mo.group(1)
     except EnvironmentError:
         pass
     return keywords
@@ -161,10 +158,14 @@ def git_get_keywords(versionfile_abs):
 @register_vcs_handler("git", "keywords")
 def git_versions_from_keywords(keywords, tag_prefix, verbose):
     """Get version information from git keywords."""
-    if not keywords:
-        raise NotThisMethod("no keywords at all, weird")
+    if "refnames" not in keywords:
+        raise NotThisMethod("Short version file found")
     date = keywords.get("date")
     if date is not None:
+        # Use only the last line.  Previous lines may contain GPG signature
+        # information.
+        date = date.splitlines()[-1]
+
         # git-2.2.0 added "%cI", which expands to an ISO-8601 -compliant
         # datestamp. However we prefer "%ci" (which expands to an "ISO-8601
         # -like" string, which we must then edit to make compliant), because
@@ -177,11 +178,11 @@ def git_versions_from_keywords(keywords, tag_prefix, verbose):
         if verbose:
             print("keywords are unexpanded, not using")
         raise NotThisMethod("unexpanded keywords, not a git-archive tarball")
-    refs = set([r.strip() for r in refnames.strip("()").split(",")])
+    refs = {r.strip() for r in refnames.strip("()").split(",")}
     # starting in git-1.8.3, tags are listed as "tag: foo-1.0" instead of
     # just "foo-1.0". If we see a "tag: " prefix, prefer those.
     TAG = "tag: "
-    tags = set([r[len(TAG):] for r in refs if r.startswith(TAG)])
+    tags = {r[len(TAG):] for r in refs if r.startswith(TAG)}
     if not tags:
         # Either we're using git < 1.8.3, or there really are no tags. We use
         # a heuristic: assume all version tags have a digit. The old git %d
@@ -190,7 +191,7 @@ def git_versions_from_keywords(keywords, tag_prefix, verbose):
         # between branches and tags. By ignoring refnames without digits, we
         # filter out many common branch names like "release" and
         # "stabilization", as well as "HEAD" and "master".
-        tags = set([r for r in refs if re.search(r'\d', r)])
+        tags = {r for r in refs if re.search(r'\d', r)}
         if verbose:
             print("discarding '%s', no digits" % ",".join(refs - tags))
     if verbose:
@@ -199,6 +200,11 @@ def git_versions_from_keywords(keywords, tag_prefix, verbose):
         # sorting will prefer e.g. "2.0" over "2.0rc1"
         if ref.startswith(tag_prefix):
             r = ref[len(tag_prefix):]
+            # Filter out refs that exactly match prefix or that don't start
+            # with a number once the prefix is stripped (mostly a concern
+            # when prefix is '')
+            if not re.match(r'\d', r):
+                continue
             if verbose:
                 print("picking %s" % r)
             return {"version": r,
@@ -214,7 +220,7 @@ def git_versions_from_keywords(keywords, tag_prefix, verbose):
 
 
 @register_vcs_handler("git", "pieces_from_vcs")
-def git_pieces_from_vcs(tag_prefix, root, verbose, run_command=run_command):
+def git_pieces_from_vcs(tag_prefix, root, verbose, runner=run_command):
     """Get version from 'git describe' in the root of the source tree.
 
     This only gets called if the git-archive 'subst' keywords were *not*
@@ -225,8 +231,8 @@ def git_pieces_from_vcs(tag_prefix, root, verbose, run_command=run_command):
     if sys.platform == "win32":
         GITS = ["git.cmd", "git.exe"]
 
-    out, rc = run_command(GITS, ["rev-parse", "--git-dir"], cwd=root,
-                          hide_stderr=True)
+    _, rc = runner(GITS, ["rev-parse", "--git-dir"], cwd=root,
+                   hide_stderr=True)
     if rc != 0:
         if verbose:
             print("Directory %s not under git control" % root)
@@ -234,15 +240,15 @@ def git_pieces_from_vcs(tag_prefix, root, verbose, run_command=run_command):
 
     # if there is a tag matching tag_prefix, this yields TAG-NUM-gHEX[-dirty]
     # if there isn't one, this yields HEX[-dirty] (no NUM)
-    describe_out, rc = run_command(GITS, ["describe", "--tags", "--dirty",
-                                          "--always", "--long",
-                                          "--match", "%s*" % tag_prefix],
-                                   cwd=root)
+    describe_out, rc = runner(GITS, ["describe", "--tags", "--dirty",
+                                     "--always", "--long",
+                                     "--match", "%s*" % tag_prefix],
+                              cwd=root)
     # --long was added in git-1.5.5
     if describe_out is None:
         raise NotThisMethod("'git describe' failed")
     describe_out = describe_out.strip()
-    full_out, rc = run_command(GITS, ["rev-parse", "HEAD"], cwd=root)
+    full_out, rc = runner(GITS, ["rev-parse", "HEAD"], cwd=root)
     if full_out is None:
         raise NotThisMethod("'git rev-parse' failed")
     full_out = full_out.strip()
@@ -252,6 +258,39 @@ def git_pieces_from_vcs(tag_prefix, root, verbose, run_command=run_command):
     pieces["short"] = full_out[:7]  # maybe improved later
     pieces["error"] = None
 
+    branch_name, rc = runner(GITS, ["rev-parse", "--abbrev-ref", "HEAD"],
+                             cwd=root)
+    # --abbrev-ref was added in git-1.6.3
+    if rc != 0 or branch_name is None:
+        raise NotThisMethod("'git rev-parse --abbrev-ref' returned error")
+    branch_name = branch_name.strip()
+
+    if branch_name == "HEAD":
+        # If we aren't exactly on a branch, pick a branch which represents
+        # the current commit. If all else fails, we are on a branchless
+        # commit.
+        branches, rc = runner(GITS, ["branch", "--contains"], cwd=root)
+        # --contains was added in git-1.5.4
+        if rc != 0 or branches is None:
+            raise NotThisMethod("'git branch --contains' returned error")
+        branches = branches.split("\n")
+
+        # Remove the first line if we're running detached
+        if "(" in branches[0]:
+            branches.pop(0)
+
+        # Strip off the leading "* " from the list of branches.
+        branches = [branch[2:] for branch in branches]
+        if "master" in branches:
+            branch_name = "master"
+        elif not branches:
+            branch_name = None
+        else:
+            # Pick the first branch that is returned. Good or bad.
+            branch_name = branches[0]
+
+    pieces["branch"] = branch_name
+
     # parse describe_out. It will be like TAG-NUM-gHEX[-dirty] or HEX[-dirty]
     # TAG might have hyphens.
     git_describe = describe_out
@@ -268,7 +307,7 @@ def git_pieces_from_vcs(tag_prefix, root, verbose, run_command=run_command):
         # TAG-NUM-gHEX
         mo = re.search(r'^(.+)-(\d+)-g([0-9a-f]+)$', git_describe)
         if not mo:
-            # unparsable. Maybe git-describe is misbehaving?
+            # unparseable. Maybe git-describe is misbehaving?
             pieces["error"] = ("unable to parse git-describe output: '%s'"
                                % describe_out)
             return pieces
@@ -293,13 +332,14 @@ def git_pieces_from_vcs(tag_prefix, root, verbose, run_command=run_command):
     else:
         # HEX: no tags
         pieces["closest-tag"] = None
-        count_out, rc = run_command(GITS, ["rev-list", "HEAD", "--count"],
-                                    cwd=root)
+        count_out, rc = runner(GITS, ["rev-list", "HEAD", "--count"], cwd=root)
         pieces["distance"] = int(count_out)  # total number of commits
 
     # commit date: see ISO-8601 comment in git_versions_from_keywords()
-    date = run_command(GITS, ["show", "-s", "--format=%ci", "HEAD"],
-                       cwd=root)[0].strip()
+    date = runner(GITS, ["show", "-s", "--format=%ci", "HEAD"], cwd=root)[0].strip()
+    # Use only the last line.  Previous lines may contain GPG signature
+    # information.
+    date = date.splitlines()[-1]
     pieces["date"] = date.strip().replace(" ", "T", 1).replace(" ", "", 1)
 
     return pieces
@@ -337,19 +377,49 @@ def render_pep440(pieces):
     return rendered
 
 
+def render_pep440_branch(pieces):
+    """TAG[[.dev0]+DISTANCE.gHEX[.dirty]] .
+
+    The ".dev0" means not master branch. Note that .dev0 sorts backwards
+    (a feature branch will appear "older" than the master branch).
+
+    Exceptions:
+    1: no tags. 0[.dev0]+untagged.DISTANCE.gHEX[.dirty]
+    """
+    if pieces["closest-tag"]:
+        rendered = pieces["closest-tag"]
+        if pieces["distance"] or pieces["dirty"]:
+            if pieces["branch"] != "master":
+                rendered += ".dev0"
+            rendered += plus_or_dot(pieces)
+            rendered += "%d.g%s" % (pieces["distance"], pieces["short"])
+            if pieces["dirty"]:
+                rendered += ".dirty"
+    else:
+        # exception #1
+        rendered = "0"
+        if pieces["branch"] != "master":
+            rendered += ".dev0"
+        rendered += "+untagged.%d.g%s" % (pieces["distance"],
+                                          pieces["short"])
+        if pieces["dirty"]:
+            rendered += ".dirty"
+    return rendered
+
+
 def render_pep440_pre(pieces):
-    """TAG[.post.devDISTANCE] -- No -dirty.
+    """TAG[.post0.devDISTANCE] -- No -dirty.
 
     Exceptions:
-    1: no tags. 0.post.devDISTANCE
+    1: no tags. 0.post0.devDISTANCE
     """
     if pieces["closest-tag"]:
         rendered = pieces["closest-tag"]
         if pieces["distance"]:
-            rendered += ".post.dev%d" % pieces["distance"]
+            rendered += ".post0.dev%d" % pieces["distance"]
     else:
         # exception #1
-        rendered = "0.post.dev%d" % pieces["distance"]
+        rendered = "0.post0.dev%d" % pieces["distance"]
     return rendered
 
 
@@ -380,12 +450,41 @@ def render_pep440_post(pieces):
     return rendered
 
 
+def render_pep440_post_branch(pieces):
+    """TAG[.postDISTANCE[.dev0]+gHEX[.dirty]] .
+
+    The ".dev0" means not master branch.
+
+    Exceptions:
+    1: no tags. 0.postDISTANCE[.dev0]+gHEX[.dirty]
+    """
+    if pieces["closest-tag"]:
+        rendered = pieces["closest-tag"]
+        if pieces["distance"] or pieces["dirty"]:
+            rendered += ".post%d" % pieces["distance"]
+            if pieces["branch"] != "master":
+                rendered += ".dev0"
+            rendered += plus_or_dot(pieces)
+            rendered += "g%s" % pieces["short"]
+            if pieces["dirty"]:
+                rendered += ".dirty"
+    else:
+        # exception #1
+        rendered = "0.post%d" % pieces["distance"]
+        if pieces["branch"] != "master":
+            rendered += ".dev0"
+        rendered += "+g%s" % pieces["short"]
+        if pieces["dirty"]:
+            rendered += ".dirty"
+    return rendered
+
+
 def render_pep440_old(pieces):
     """TAG[.postDISTANCE[.dev0]] .
 
     The ".dev0" means dirty.
 
-    Eexceptions:
+    Exceptions:
     1: no tags. 0.postDISTANCE[.dev0]
     """
     if pieces["closest-tag"]:
@@ -456,10 +555,14 @@ def render(pieces, style):
 
     if style == "pep440":
         rendered = render_pep440(pieces)
+    elif style == "pep440-branch":
+        rendered = render_pep440_branch(pieces)
     elif style == "pep440-pre":
         rendered = render_pep440_pre(pieces)
     elif style == "pep440-post":
         rendered = render_pep440_post(pieces)
+    elif style == "pep440-post-branch":
+        rendered = render_pep440_post_branch(pieces)
     elif style == "pep440-old":
         rendered = render_pep440_old(pieces)
     elif style == "git-describe":
@@ -495,7 +598,7 @@ def get_versions():
         # versionfile_source is the relative path from the top of the source
         # tree (where the .git directory might live) to this file. Invert
         # this to find the root from __file__.
-        for i in cfg.versionfile_source.split(os.path.sep):
+        for _ in cfg.versionfile_source.split('/'):
             root = os.path.dirname(root)
     except NameError:
         return {"version": "0+unknown", "full-revisionid": None,
diff --git a/versioneer.py b/versioneer.py
--- a/versioneer.py
+++ b/versioneer.py
@@ -1,5 +1,5 @@
 
-# Version: 0.18
+# Version: 0.20
 
 """The Versioneer - like a rocketeer, but for versions.
 
@@ -7,16 +7,12 @@
 ==============
 
 * like a rocketeer, but for versions!
-* https://github.com/warner/python-versioneer
+* https://github.com/python-versioneer/python-versioneer
 * Brian Warner
 * License: Public Domain
-* Compatible With: python2.6, 2.7, 3.2, 3.3, 3.4, 3.5, 3.6, and pypy
-* [![Latest Version]
-(https://pypip.in/version/versioneer/badge.svg?style=flat)
-](https://pypi.python.org/pypi/versioneer/)
-* [![Build Status]
-(https://travis-ci.org/warner/python-versioneer.png?branch=master)
-](https://travis-ci.org/warner/python-versioneer)
+* Compatible with: Python 3.6, 3.7, 3.8, 3.9 and pypy3
+* [![Latest Version][pypi-image]][pypi-url]
+* [![Build Status][travis-image]][travis-url]
 
 This is a tool for managing a recorded version number in distutils-based
 python projects. The goal is to remove the tedious and error-prone "update
@@ -27,9 +23,10 @@
 
 ## Quick Install
 
-* `pip install versioneer` to somewhere to your $PATH
-* add a `[versioneer]` section to your setup.cfg (see below)
+* `pip install versioneer` to somewhere in your $PATH
+* add a `[versioneer]` section to your setup.cfg (see [Install](INSTALL.md))
 * run `versioneer install` in your source tree, commit the results
+* Verify version information with `python setup.py version`
 
 ## Version Identifiers
 
@@ -61,7 +58,7 @@
 for example `git describe --tags --dirty --always` reports things like
 "0.7-1-g574ab98-dirty" to indicate that the checkout is one revision past the
 0.7 tag, has a unique revision id of "574ab98", and is "dirty" (it has
-uncommitted changes.
+uncommitted changes).
 
 The version identifier is used for multiple purposes:
 
@@ -166,7 +163,7 @@
 
 Some situations are known to cause problems for Versioneer. This details the
 most significant ones. More can be found on Github
-[issues page](https://github.com/warner/python-versioneer/issues).
+[issues page](https://github.com/python-versioneer/python-versioneer/issues).
 
 ### Subprojects
 
@@ -180,7 +177,7 @@
   `setup.cfg`, and `tox.ini`. Projects like these produce multiple PyPI
   distributions (and upload multiple independently-installable tarballs).
 * Source trees whose main purpose is to contain a C library, but which also
-  provide bindings to Python (and perhaps other langauges) in subdirectories.
+  provide bindings to Python (and perhaps other languages) in subdirectories.
 
 Versioneer will look for `.git` in parent directories, and most operations
 should get the right version string. However `pip` and `setuptools` have bugs
@@ -194,9 +191,9 @@
 Pip-8.1.1 is known to have this problem, but hopefully it will get fixed in
 some later version.
 
-[Bug #38](https://github.com/warner/python-versioneer/issues/38) is tracking
+[Bug #38](https://github.com/python-versioneer/python-versioneer/issues/38) is tracking
 this issue. The discussion in
-[PR #61](https://github.com/warner/python-versioneer/pull/61) describes the
+[PR #61](https://github.com/python-versioneer/python-versioneer/pull/61) describes the
 issue from the Versioneer side in more detail.
 [pip PR#3176](https://github.com/pypa/pip/pull/3176) and
 [pip PR#3615](https://github.com/pypa/pip/pull/3615) contain work to improve
@@ -224,22 +221,10 @@
 cause egg_info to be rebuilt (including `sdist`, `wheel`, and installing into
 a different virtualenv), so this can be surprising.
 
-[Bug #83](https://github.com/warner/python-versioneer/issues/83) describes
+[Bug #83](https://github.com/python-versioneer/python-versioneer/issues/83) describes
 this one, but upgrading to a newer version of setuptools should probably
 resolve it.
 
-### Unicode version strings
-
-While Versioneer works (and is continually tested) with both Python 2 and
-Python 3, it is not entirely consistent with bytes-vs-unicode distinctions.
-Newer releases probably generate unicode version strings on py2. It's not
-clear that this is wrong, but it may be surprising for applications when then
-write these strings to a network connection or include them in bytes-oriented
-APIs like cryptographic checksums.
-
-[Bug #71](https://github.com/warner/python-versioneer/issues/71) investigates
-this question.
-
 
 ## Updating Versioneer
 
@@ -265,6 +250,14 @@
 direction and include code from all supported VCS systems, reducing the
 number of intermediate scripts.
 
+## Similar projects
+
+* [setuptools_scm](https://github.com/pypa/setuptools_scm/) - a non-vendored build-time
+  dependency
+* [minver](https://github.com/jbweston/miniver) - a lightweight reimplementation of
+  versioneer
+* [versioningit](https://github.com/jwodder/versioningit) - a PEP 518-based setuptools
+  plugin
 
 ## License
 
@@ -274,12 +267,15 @@
 Dedication" license (CC0-1.0), as described in
 https://creativecommons.org/publicdomain/zero/1.0/ .
 
+[pypi-image]: https://img.shields.io/pypi/v/versioneer.svg
+[pypi-url]: https://pypi.python.org/pypi/versioneer/
+[travis-image]:
+https://img.shields.io/travis/com/python-versioneer/python-versioneer.svg
+[travis-url]: https://travis-ci.com/github/python-versioneer/python-versioneer
+
 """
 
-try:
-    import configparser
-except ImportError:
-    import ConfigParser as configparser
+import configparser
 import errno
 import json
 import os
@@ -288,7 +284,7 @@
 import sys
 
 
-class VersioneerConfig:
+class VersioneerConfig:  # pylint: disable=too-few-public-methods # noqa
     """Container for Versioneer configuration parameters."""
 
 
@@ -320,12 +316,12 @@ def get_root():
         # module-import table will cache the first one. So we can't use
         # os.path.dirname(__file__), as that will find whichever
         # versioneer.py was first imported, even in later projects.
-        me = os.path.realpath(os.path.abspath(__file__))
-        me_dir = os.path.normcase(os.path.splitext(me)[0])
+        my_path = os.path.realpath(os.path.abspath(__file__))
+        me_dir = os.path.normcase(os.path.splitext(my_path)[0])
         vsr_dir = os.path.normcase(os.path.splitext(versioneer_py)[0])
         if me_dir != vsr_dir:
             print("Warning: build in %s is using versioneer.py from %s"
-                  % (os.path.dirname(me), versioneer_py))
+                  % (os.path.dirname(my_path), versioneer_py))
     except NameError:
         pass
     return root
@@ -338,25 +334,25 @@ def get_config_from_root(root):
     # configparser.NoOptionError (if it lacks "VCS="). See the docstring at
     # the top of versioneer.py for instructions on writing your setup.cfg .
     setup_cfg = os.path.join(root, "setup.cfg")
-    parser = configparser.SafeConfigParser()
-    with open(setup_cfg, "r") as f:
-        parser.readfp(f)
+    parser = configparser.ConfigParser()
+    with open(setup_cfg, "r") as cfg_file:
+        parser.read_file(cfg_file)
     VCS = parser.get("versioneer", "VCS")  # mandatory
 
-    def get(parser, name):
-        if parser.has_option("versioneer", name):
-            return parser.get("versioneer", name)
-        return None
+    # Dict-like interface for non-mandatory entries
+    section = parser["versioneer"]
+
+    # pylint:disable=attribute-defined-outside-init # noqa
     cfg = VersioneerConfig()
     cfg.VCS = VCS
-    cfg.style = get(parser, "style") or ""
-    cfg.versionfile_source = get(parser, "versionfile_source")
-    cfg.versionfile_build = get(parser, "versionfile_build")
-    cfg.tag_prefix = get(parser, "tag_prefix")
+    cfg.style = section.get("style", "")
+    cfg.versionfile_source = section.get("versionfile_source")
+    cfg.versionfile_build = section.get("versionfile_build")
+    cfg.tag_prefix = section.get("tag_prefix")
     if cfg.tag_prefix in ("''", '""'):
         cfg.tag_prefix = ""
-    cfg.parentdir_prefix = get(parser, "parentdir_prefix")
-    cfg.verbose = get(parser, "verbose")
+    cfg.parentdir_prefix = section.get("parentdir_prefix")
+    cfg.verbose = section.get("verbose")
     return cfg
 
 
@@ -370,29 +366,28 @@ class NotThisMethod(Exception):
 
 
 def register_vcs_handler(vcs, method):  # decorator
-    """Decorator to mark a method as the handler for a particular VCS."""
+    """Create decorator to mark a method as the handler of a VCS."""
     def decorate(f):
         """Store f in HANDLERS[vcs][method]."""
-        if vcs not in HANDLERS:
-            HANDLERS[vcs] = {}
-        HANDLERS[vcs][method] = f
+        HANDLERS.setdefault(vcs, {})[method] = f
         return f
     return decorate
 
 
+# pylint:disable=too-many-arguments,consider-using-with # noqa
 def run_command(commands, args, cwd=None, verbose=False, hide_stderr=False,
                 env=None):
     """Call the given command(s)."""
     assert isinstance(commands, list)
-    p = None
-    for c in commands:
+    process = None
+    for command in commands:
         try:
-            dispcmd = str([c] + args)
+            dispcmd = str([command] + args)
             # remember shell=False, so use git.cmd on windows, not just git
-            p = subprocess.Popen([c] + args, cwd=cwd, env=env,
-                                 stdout=subprocess.PIPE,
-                                 stderr=(subprocess.PIPE if hide_stderr
-                                         else None))
+            process = subprocess.Popen([command] + args, cwd=cwd, env=env,
+                                       stdout=subprocess.PIPE,
+                                       stderr=(subprocess.PIPE if hide_stderr
+                                               else None))
             break
         except EnvironmentError:
             e = sys.exc_info()[1]
@@ -406,18 +401,16 @@ def run_command(commands, args, cwd=None, verbose=False, hide_stderr=False,
         if verbose:
             print("unable to find command, tried %s" % (commands,))
         return None, None
-    stdout = p.communicate()[0].strip()
-    if sys.version_info[0] >= 3:
-        stdout = stdout.decode()
-    if p.returncode != 0:
+    stdout = process.communicate()[0].strip().decode()
+    if process.returncode != 0:
         if verbose:
             print("unable to run %s (error)" % dispcmd)
             print("stdout was %s" % stdout)
-        return None, p.returncode
-    return stdout, p.returncode
+        return None, process.returncode
+    return stdout, process.returncode
 
 
-LONG_VERSION_PY['git'] = '''
+LONG_VERSION_PY['git'] = r'''
 # This file helps to compute a version number in source trees obtained from
 # git-archive tarball (such as those provided by githubs download-from-tag
 # feature). Distribution tarballs (built by setup.py sdist) and build
@@ -425,7 +418,7 @@ def run_command(commands, args, cwd=None, verbose=False, hide_stderr=False,
 # that just contains the computed version number.
 
 # This file is released into the public domain. Generated by
-# versioneer-0.18 (https://github.com/warner/python-versioneer)
+# versioneer-0.20 (https://github.com/python-versioneer/python-versioneer)
 
 """Git implementation of _version.py."""
 
@@ -449,7 +442,7 @@ def get_keywords():
     return keywords
 
 
-class VersioneerConfig:
+class VersioneerConfig:  # pylint: disable=too-few-public-methods
     """Container for Versioneer configuration parameters."""
 
 
@@ -476,7 +469,7 @@ class NotThisMethod(Exception):
 
 
 def register_vcs_handler(vcs, method):  # decorator
-    """Decorator to mark a method as the handler for a particular VCS."""
+    """Create decorator to mark a method as the handler of a VCS."""
     def decorate(f):
         """Store f in HANDLERS[vcs][method]."""
         if vcs not in HANDLERS:
@@ -486,19 +479,20 @@ def decorate(f):
     return decorate
 
 
+# pylint:disable=too-many-arguments,consider-using-with # noqa
 def run_command(commands, args, cwd=None, verbose=False, hide_stderr=False,
                 env=None):
     """Call the given command(s)."""
     assert isinstance(commands, list)
-    p = None
-    for c in commands:
+    process = None
+    for command in commands:
         try:
-            dispcmd = str([c] + args)
+            dispcmd = str([command] + args)
             # remember shell=False, so use git.cmd on windows, not just git
-            p = subprocess.Popen([c] + args, cwd=cwd, env=env,
-                                 stdout=subprocess.PIPE,
-                                 stderr=(subprocess.PIPE if hide_stderr
-                                         else None))
+            process = subprocess.Popen([command] + args, cwd=cwd, env=env,
+                                       stdout=subprocess.PIPE,
+                                       stderr=(subprocess.PIPE if hide_stderr
+                                               else None))
             break
         except EnvironmentError:
             e = sys.exc_info()[1]
@@ -512,15 +506,13 @@ def run_command(commands, args, cwd=None, verbose=False, hide_stderr=False,
         if verbose:
             print("unable to find command, tried %%s" %% (commands,))
         return None, None
-    stdout = p.communicate()[0].strip()
-    if sys.version_info[0] >= 3:
-        stdout = stdout.decode()
-    if p.returncode != 0:
+    stdout = process.communicate()[0].strip().decode()
+    if process.returncode != 0:
         if verbose:
             print("unable to run %%s (error)" %% dispcmd)
             print("stdout was %%s" %% stdout)
-        return None, p.returncode
-    return stdout, p.returncode
+        return None, process.returncode
+    return stdout, process.returncode
 
 
 def versions_from_parentdir(parentdir_prefix, root, verbose):
@@ -532,15 +524,14 @@ def versions_from_parentdir(parentdir_prefix, root, verbose):
     """
     rootdirs = []
 
-    for i in range(3):
+    for _ in range(3):
         dirname = os.path.basename(root)
         if dirname.startswith(parentdir_prefix):
             return {"version": dirname[len(parentdir_prefix):],
                     "full-revisionid": None,
                     "dirty": False, "error": None, "date": None}
-        else:
-            rootdirs.append(root)
-            root = os.path.dirname(root)  # up a level
+        rootdirs.append(root)
+        root = os.path.dirname(root)  # up a level
 
     if verbose:
         print("Tried directories %%s but none started with prefix %%s" %%
@@ -557,21 +548,20 @@ def git_get_keywords(versionfile_abs):
     # _version.py.
     keywords = {}
     try:
-        f = open(versionfile_abs, "r")
-        for line in f.readlines():
-            if line.strip().startswith("git_refnames ="):
-                mo = re.search(r'=\s*"(.*)"', line)
-                if mo:
-                    keywords["refnames"] = mo.group(1)
-            if line.strip().startswith("git_full ="):
-                mo = re.search(r'=\s*"(.*)"', line)
-                if mo:
-                    keywords["full"] = mo.group(1)
-            if line.strip().startswith("git_date ="):
-                mo = re.search(r'=\s*"(.*)"', line)
-                if mo:
-                    keywords["date"] = mo.group(1)
-        f.close()
+        with open(versionfile_abs, "r") as fobj:
+            for line in fobj:
+                if line.strip().startswith("git_refnames ="):
+                    mo = re.search(r'=\s*"(.*)"', line)
+                    if mo:
+                        keywords["refnames"] = mo.group(1)
+                if line.strip().startswith("git_full ="):
+                    mo = re.search(r'=\s*"(.*)"', line)
+                    if mo:
+                        keywords["full"] = mo.group(1)
+                if line.strip().startswith("git_date ="):
+                    mo = re.search(r'=\s*"(.*)"', line)
+                    if mo:
+                        keywords["date"] = mo.group(1)
     except EnvironmentError:
         pass
     return keywords
@@ -580,10 +570,14 @@ def git_get_keywords(versionfile_abs):
 @register_vcs_handler("git", "keywords")
 def git_versions_from_keywords(keywords, tag_prefix, verbose):
     """Get version information from git keywords."""
-    if not keywords:
-        raise NotThisMethod("no keywords at all, weird")
+    if "refnames" not in keywords:
+        raise NotThisMethod("Short version file found")
     date = keywords.get("date")
     if date is not None:
+        # Use only the last line.  Previous lines may contain GPG signature
+        # information.
+        date = date.splitlines()[-1]
+
         # git-2.2.0 added "%%cI", which expands to an ISO-8601 -compliant
         # datestamp. However we prefer "%%ci" (which expands to an "ISO-8601
         # -like" string, which we must then edit to make compliant), because
@@ -596,11 +590,11 @@ def git_versions_from_keywords(keywords, tag_prefix, verbose):
         if verbose:
             print("keywords are unexpanded, not using")
         raise NotThisMethod("unexpanded keywords, not a git-archive tarball")
-    refs = set([r.strip() for r in refnames.strip("()").split(",")])
+    refs = {r.strip() for r in refnames.strip("()").split(",")}
     # starting in git-1.8.3, tags are listed as "tag: foo-1.0" instead of
     # just "foo-1.0". If we see a "tag: " prefix, prefer those.
     TAG = "tag: "
-    tags = set([r[len(TAG):] for r in refs if r.startswith(TAG)])
+    tags = {r[len(TAG):] for r in refs if r.startswith(TAG)}
     if not tags:
         # Either we're using git < 1.8.3, or there really are no tags. We use
         # a heuristic: assume all version tags have a digit. The old git %%d
@@ -609,7 +603,7 @@ def git_versions_from_keywords(keywords, tag_prefix, verbose):
         # between branches and tags. By ignoring refnames without digits, we
         # filter out many common branch names like "release" and
         # "stabilization", as well as "HEAD" and "master".
-        tags = set([r for r in refs if re.search(r'\d', r)])
+        tags = {r for r in refs if re.search(r'\d', r)}
         if verbose:
             print("discarding '%%s', no digits" %% ",".join(refs - tags))
     if verbose:
@@ -618,6 +612,11 @@ def git_versions_from_keywords(keywords, tag_prefix, verbose):
         # sorting will prefer e.g. "2.0" over "2.0rc1"
         if ref.startswith(tag_prefix):
             r = ref[len(tag_prefix):]
+            # Filter out refs that exactly match prefix or that don't start
+            # with a number once the prefix is stripped (mostly a concern
+            # when prefix is '')
+            if not re.match(r'\d', r):
+                continue
             if verbose:
                 print("picking %%s" %% r)
             return {"version": r,
@@ -633,7 +632,7 @@ def git_versions_from_keywords(keywords, tag_prefix, verbose):
 
 
 @register_vcs_handler("git", "pieces_from_vcs")
-def git_pieces_from_vcs(tag_prefix, root, verbose, run_command=run_command):
+def git_pieces_from_vcs(tag_prefix, root, verbose, runner=run_command):
     """Get version from 'git describe' in the root of the source tree.
 
     This only gets called if the git-archive 'subst' keywords were *not*
@@ -644,8 +643,8 @@ def git_pieces_from_vcs(tag_prefix, root, verbose, run_command=run_command):
     if sys.platform == "win32":
         GITS = ["git.cmd", "git.exe"]
 
-    out, rc = run_command(GITS, ["rev-parse", "--git-dir"], cwd=root,
-                          hide_stderr=True)
+    _, rc = runner(GITS, ["rev-parse", "--git-dir"], cwd=root,
+                   hide_stderr=True)
     if rc != 0:
         if verbose:
             print("Directory %%s not under git control" %% root)
@@ -653,15 +652,15 @@ def git_pieces_from_vcs(tag_prefix, root, verbose, run_command=run_command):
 
     # if there is a tag matching tag_prefix, this yields TAG-NUM-gHEX[-dirty]
     # if there isn't one, this yields HEX[-dirty] (no NUM)
-    describe_out, rc = run_command(GITS, ["describe", "--tags", "--dirty",
-                                          "--always", "--long",
-                                          "--match", "%%s*" %% tag_prefix],
-                                   cwd=root)
+    describe_out, rc = runner(GITS, ["describe", "--tags", "--dirty",
+                                     "--always", "--long",
+                                     "--match", "%%s*" %% tag_prefix],
+                              cwd=root)
     # --long was added in git-1.5.5
     if describe_out is None:
         raise NotThisMethod("'git describe' failed")
     describe_out = describe_out.strip()
-    full_out, rc = run_command(GITS, ["rev-parse", "HEAD"], cwd=root)
+    full_out, rc = runner(GITS, ["rev-parse", "HEAD"], cwd=root)
     if full_out is None:
         raise NotThisMethod("'git rev-parse' failed")
     full_out = full_out.strip()
@@ -671,6 +670,39 @@ def git_pieces_from_vcs(tag_prefix, root, verbose, run_command=run_command):
     pieces["short"] = full_out[:7]  # maybe improved later
     pieces["error"] = None
 
+    branch_name, rc = runner(GITS, ["rev-parse", "--abbrev-ref", "HEAD"],
+                             cwd=root)
+    # --abbrev-ref was added in git-1.6.3
+    if rc != 0 or branch_name is None:
+        raise NotThisMethod("'git rev-parse --abbrev-ref' returned error")
+    branch_name = branch_name.strip()
+
+    if branch_name == "HEAD":
+        # If we aren't exactly on a branch, pick a branch which represents
+        # the current commit. If all else fails, we are on a branchless
+        # commit.
+        branches, rc = runner(GITS, ["branch", "--contains"], cwd=root)
+        # --contains was added in git-1.5.4
+        if rc != 0 or branches is None:
+            raise NotThisMethod("'git branch --contains' returned error")
+        branches = branches.split("\n")
+
+        # Remove the first line if we're running detached
+        if "(" in branches[0]:
+            branches.pop(0)
+
+        # Strip off the leading "* " from the list of branches.
+        branches = [branch[2:] for branch in branches]
+        if "master" in branches:
+            branch_name = "master"
+        elif not branches:
+            branch_name = None
+        else:
+            # Pick the first branch that is returned. Good or bad.
+            branch_name = branches[0]
+
+    pieces["branch"] = branch_name
+
     # parse describe_out. It will be like TAG-NUM-gHEX[-dirty] or HEX[-dirty]
     # TAG might have hyphens.
     git_describe = describe_out
@@ -712,13 +744,14 @@ def git_pieces_from_vcs(tag_prefix, root, verbose, run_command=run_command):
     else:
         # HEX: no tags
         pieces["closest-tag"] = None
-        count_out, rc = run_command(GITS, ["rev-list", "HEAD", "--count"],
-                                    cwd=root)
+        count_out, rc = runner(GITS, ["rev-list", "HEAD", "--count"], cwd=root)
         pieces["distance"] = int(count_out)  # total number of commits
 
     # commit date: see ISO-8601 comment in git_versions_from_keywords()
-    date = run_command(GITS, ["show", "-s", "--format=%%ci", "HEAD"],
-                       cwd=root)[0].strip()
+    date = runner(GITS, ["show", "-s", "--format=%%ci", "HEAD"], cwd=root)[0].strip()
+    # Use only the last line.  Previous lines may contain GPG signature
+    # information.
+    date = date.splitlines()[-1]
     pieces["date"] = date.strip().replace(" ", "T", 1).replace(" ", "", 1)
 
     return pieces
@@ -756,19 +789,49 @@ def render_pep440(pieces):
     return rendered
 
 
+def render_pep440_branch(pieces):
+    """TAG[[.dev0]+DISTANCE.gHEX[.dirty]] .
+
+    The ".dev0" means not master branch. Note that .dev0 sorts backwards
+    (a feature branch will appear "older" than the master branch).
+
+    Exceptions:
+    1: no tags. 0[.dev0]+untagged.DISTANCE.gHEX[.dirty]
+    """
+    if pieces["closest-tag"]:
+        rendered = pieces["closest-tag"]
+        if pieces["distance"] or pieces["dirty"]:
+            if pieces["branch"] != "master":
+                rendered += ".dev0"
+            rendered += plus_or_dot(pieces)
+            rendered += "%%d.g%%s" %% (pieces["distance"], pieces["short"])
+            if pieces["dirty"]:
+                rendered += ".dirty"
+    else:
+        # exception #1
+        rendered = "0"
+        if pieces["branch"] != "master":
+            rendered += ".dev0"
+        rendered += "+untagged.%%d.g%%s" %% (pieces["distance"],
+                                          pieces["short"])
+        if pieces["dirty"]:
+            rendered += ".dirty"
+    return rendered
+
+
 def render_pep440_pre(pieces):
-    """TAG[.post.devDISTANCE] -- No -dirty.
+    """TAG[.post0.devDISTANCE] -- No -dirty.
 
     Exceptions:
-    1: no tags. 0.post.devDISTANCE
+    1: no tags. 0.post0.devDISTANCE
     """
     if pieces["closest-tag"]:
         rendered = pieces["closest-tag"]
         if pieces["distance"]:
-            rendered += ".post.dev%%d" %% pieces["distance"]
+            rendered += ".post0.dev%%d" %% pieces["distance"]
     else:
         # exception #1
-        rendered = "0.post.dev%%d" %% pieces["distance"]
+        rendered = "0.post0.dev%%d" %% pieces["distance"]
     return rendered
 
 
@@ -799,12 +862,41 @@ def render_pep440_post(pieces):
     return rendered
 
 
+def render_pep440_post_branch(pieces):
+    """TAG[.postDISTANCE[.dev0]+gHEX[.dirty]] .
+
+    The ".dev0" means not master branch.
+
+    Exceptions:
+    1: no tags. 0.postDISTANCE[.dev0]+gHEX[.dirty]
+    """
+    if pieces["closest-tag"]:
+        rendered = pieces["closest-tag"]
+        if pieces["distance"] or pieces["dirty"]:
+            rendered += ".post%%d" %% pieces["distance"]
+            if pieces["branch"] != "master":
+                rendered += ".dev0"
+            rendered += plus_or_dot(pieces)
+            rendered += "g%%s" %% pieces["short"]
+            if pieces["dirty"]:
+                rendered += ".dirty"
+    else:
+        # exception #1
+        rendered = "0.post%%d" %% pieces["distance"]
+        if pieces["branch"] != "master":
+            rendered += ".dev0"
+        rendered += "+g%%s" %% pieces["short"]
+        if pieces["dirty"]:
+            rendered += ".dirty"
+    return rendered
+
+
 def render_pep440_old(pieces):
     """TAG[.postDISTANCE[.dev0]] .
 
     The ".dev0" means dirty.
 
-    Eexceptions:
+    Exceptions:
     1: no tags. 0.postDISTANCE[.dev0]
     """
     if pieces["closest-tag"]:
@@ -875,10 +967,14 @@ def render(pieces, style):
 
     if style == "pep440":
         rendered = render_pep440(pieces)
+    elif style == "pep440-branch":
+        rendered = render_pep440_branch(pieces)
     elif style == "pep440-pre":
         rendered = render_pep440_pre(pieces)
     elif style == "pep440-post":
         rendered = render_pep440_post(pieces)
+    elif style == "pep440-post-branch":
+        rendered = render_pep440_post_branch(pieces)
     elif style == "pep440-old":
         rendered = render_pep440_old(pieces)
     elif style == "git-describe":
@@ -914,7 +1010,7 @@ def get_versions():
         # versionfile_source is the relative path from the top of the source
         # tree (where the .git directory might live) to this file. Invert
         # this to find the root from __file__.
-        for i in cfg.versionfile_source.split('/'):
+        for _ in cfg.versionfile_source.split('/'):
             root = os.path.dirname(root)
     except NameError:
         return {"version": "0+unknown", "full-revisionid": None,
@@ -949,21 +1045,20 @@ def git_get_keywords(versionfile_abs):
     # _version.py.
     keywords = {}
     try:
-        f = open(versionfile_abs, "r")
-        for line in f.readlines():
-            if line.strip().startswith("git_refnames ="):
-                mo = re.search(r'=\s*"(.*)"', line)
-                if mo:
-                    keywords["refnames"] = mo.group(1)
-            if line.strip().startswith("git_full ="):
-                mo = re.search(r'=\s*"(.*)"', line)
-                if mo:
-                    keywords["full"] = mo.group(1)
-            if line.strip().startswith("git_date ="):
-                mo = re.search(r'=\s*"(.*)"', line)
-                if mo:
-                    keywords["date"] = mo.group(1)
-        f.close()
+        with open(versionfile_abs, "r") as fobj:
+            for line in fobj:
+                if line.strip().startswith("git_refnames ="):
+                    mo = re.search(r'=\s*"(.*)"', line)
+                    if mo:
+                        keywords["refnames"] = mo.group(1)
+                if line.strip().startswith("git_full ="):
+                    mo = re.search(r'=\s*"(.*)"', line)
+                    if mo:
+                        keywords["full"] = mo.group(1)
+                if line.strip().startswith("git_date ="):
+                    mo = re.search(r'=\s*"(.*)"', line)
+                    if mo:
+                        keywords["date"] = mo.group(1)
     except EnvironmentError:
         pass
     return keywords
@@ -972,10 +1067,14 @@ def git_get_keywords(versionfile_abs):
 @register_vcs_handler("git", "keywords")
 def git_versions_from_keywords(keywords, tag_prefix, verbose):
     """Get version information from git keywords."""
-    if not keywords:
-        raise NotThisMethod("no keywords at all, weird")
+    if "refnames" not in keywords:
+        raise NotThisMethod("Short version file found")
     date = keywords.get("date")
     if date is not None:
+        # Use only the last line.  Previous lines may contain GPG signature
+        # information.
+        date = date.splitlines()[-1]
+
         # git-2.2.0 added "%cI", which expands to an ISO-8601 -compliant
         # datestamp. However we prefer "%ci" (which expands to an "ISO-8601
         # -like" string, which we must then edit to make compliant), because
@@ -988,11 +1087,11 @@ def git_versions_from_keywords(keywords, tag_prefix, verbose):
         if verbose:
             print("keywords are unexpanded, not using")
         raise NotThisMethod("unexpanded keywords, not a git-archive tarball")
-    refs = set([r.strip() for r in refnames.strip("()").split(",")])
+    refs = {r.strip() for r in refnames.strip("()").split(",")}
     # starting in git-1.8.3, tags are listed as "tag: foo-1.0" instead of
     # just "foo-1.0". If we see a "tag: " prefix, prefer those.
     TAG = "tag: "
-    tags = set([r[len(TAG):] for r in refs if r.startswith(TAG)])
+    tags = {r[len(TAG):] for r in refs if r.startswith(TAG)}
     if not tags:
         # Either we're using git < 1.8.3, or there really are no tags. We use
         # a heuristic: assume all version tags have a digit. The old git %d
@@ -1001,7 +1100,7 @@ def git_versions_from_keywords(keywords, tag_prefix, verbose):
         # between branches and tags. By ignoring refnames without digits, we
         # filter out many common branch names like "release" and
         # "stabilization", as well as "HEAD" and "master".
-        tags = set([r for r in refs if re.search(r'\d', r)])
+        tags = {r for r in refs if re.search(r'\d', r)}
         if verbose:
             print("discarding '%s', no digits" % ",".join(refs - tags))
     if verbose:
@@ -1010,6 +1109,11 @@ def git_versions_from_keywords(keywords, tag_prefix, verbose):
         # sorting will prefer e.g. "2.0" over "2.0rc1"
         if ref.startswith(tag_prefix):
             r = ref[len(tag_prefix):]
+            # Filter out refs that exactly match prefix or that don't start
+            # with a number once the prefix is stripped (mostly a concern
+            # when prefix is '')
+            if not re.match(r'\d', r):
+                continue
             if verbose:
                 print("picking %s" % r)
             return {"version": r,
@@ -1025,7 +1129,7 @@ def git_versions_from_keywords(keywords, tag_prefix, verbose):
 
 
 @register_vcs_handler("git", "pieces_from_vcs")
-def git_pieces_from_vcs(tag_prefix, root, verbose, run_command=run_command):
+def git_pieces_from_vcs(tag_prefix, root, verbose, runner=run_command):
     """Get version from 'git describe' in the root of the source tree.
 
     This only gets called if the git-archive 'subst' keywords were *not*
@@ -1036,8 +1140,8 @@ def git_pieces_from_vcs(tag_prefix, root, verbose, run_command=run_command):
     if sys.platform == "win32":
         GITS = ["git.cmd", "git.exe"]
 
-    out, rc = run_command(GITS, ["rev-parse", "--git-dir"], cwd=root,
-                          hide_stderr=True)
+    _, rc = runner(GITS, ["rev-parse", "--git-dir"], cwd=root,
+                   hide_stderr=True)
     if rc != 0:
         if verbose:
             print("Directory %s not under git control" % root)
@@ -1045,15 +1149,15 @@ def git_pieces_from_vcs(tag_prefix, root, verbose, run_command=run_command):
 
     # if there is a tag matching tag_prefix, this yields TAG-NUM-gHEX[-dirty]
     # if there isn't one, this yields HEX[-dirty] (no NUM)
-    describe_out, rc = run_command(GITS, ["describe", "--tags", "--dirty",
-                                          "--always", "--long",
-                                          "--match", "%s*" % tag_prefix],
-                                   cwd=root)
+    describe_out, rc = runner(GITS, ["describe", "--tags", "--dirty",
+                                     "--always", "--long",
+                                     "--match", "%s*" % tag_prefix],
+                              cwd=root)
     # --long was added in git-1.5.5
     if describe_out is None:
         raise NotThisMethod("'git describe' failed")
     describe_out = describe_out.strip()
-    full_out, rc = run_command(GITS, ["rev-parse", "HEAD"], cwd=root)
+    full_out, rc = runner(GITS, ["rev-parse", "HEAD"], cwd=root)
     if full_out is None:
         raise NotThisMethod("'git rev-parse' failed")
     full_out = full_out.strip()
@@ -1063,6 +1167,39 @@ def git_pieces_from_vcs(tag_prefix, root, verbose, run_command=run_command):
     pieces["short"] = full_out[:7]  # maybe improved later
     pieces["error"] = None
 
+    branch_name, rc = runner(GITS, ["rev-parse", "--abbrev-ref", "HEAD"],
+                             cwd=root)
+    # --abbrev-ref was added in git-1.6.3
+    if rc != 0 or branch_name is None:
+        raise NotThisMethod("'git rev-parse --abbrev-ref' returned error")
+    branch_name = branch_name.strip()
+
+    if branch_name == "HEAD":
+        # If we aren't exactly on a branch, pick a branch which represents
+        # the current commit. If all else fails, we are on a branchless
+        # commit.
+        branches, rc = runner(GITS, ["branch", "--contains"], cwd=root)
+        # --contains was added in git-1.5.4
+        if rc != 0 or branches is None:
+            raise NotThisMethod("'git branch --contains' returned error")
+        branches = branches.split("\n")
+
+        # Remove the first line if we're running detached
+        if "(" in branches[0]:
+            branches.pop(0)
+
+        # Strip off the leading "* " from the list of branches.
+        branches = [branch[2:] for branch in branches]
+        if "master" in branches:
+            branch_name = "master"
+        elif not branches:
+            branch_name = None
+        else:
+            # Pick the first branch that is returned. Good or bad.
+            branch_name = branches[0]
+
+    pieces["branch"] = branch_name
+
     # parse describe_out. It will be like TAG-NUM-gHEX[-dirty] or HEX[-dirty]
     # TAG might have hyphens.
     git_describe = describe_out
@@ -1104,13 +1241,14 @@ def git_pieces_from_vcs(tag_prefix, root, verbose, run_command=run_command):
     else:
         # HEX: no tags
         pieces["closest-tag"] = None
-        count_out, rc = run_command(GITS, ["rev-list", "HEAD", "--count"],
-                                    cwd=root)
+        count_out, rc = runner(GITS, ["rev-list", "HEAD", "--count"], cwd=root)
         pieces["distance"] = int(count_out)  # total number of commits
 
     # commit date: see ISO-8601 comment in git_versions_from_keywords()
-    date = run_command(GITS, ["show", "-s", "--format=%ci", "HEAD"],
-                       cwd=root)[0].strip()
+    date = runner(GITS, ["show", "-s", "--format=%ci", "HEAD"], cwd=root)[0].strip()
+    # Use only the last line.  Previous lines may contain GPG signature
+    # information.
+    date = date.splitlines()[-1]
     pieces["date"] = date.strip().replace(" ", "T", 1).replace(" ", "", 1)
 
     return pieces
@@ -1129,27 +1267,26 @@ def do_vcs_install(manifest_in, versionfile_source, ipy):
     if ipy:
         files.append(ipy)
     try:
-        me = __file__
-        if me.endswith(".pyc") or me.endswith(".pyo"):
-            me = os.path.splitext(me)[0] + ".py"
-        versioneer_file = os.path.relpath(me)
+        my_path = __file__
+        if my_path.endswith(".pyc") or my_path.endswith(".pyo"):
+            my_path = os.path.splitext(my_path)[0] + ".py"
+        versioneer_file = os.path.relpath(my_path)
     except NameError:
         versioneer_file = "versioneer.py"
     files.append(versioneer_file)
     present = False
     try:
-        f = open(".gitattributes", "r")
-        for line in f.readlines():
-            if line.strip().startswith(versionfile_source):
-                if "export-subst" in line.strip().split()[1:]:
-                    present = True
-        f.close()
+        with open(".gitattributes", "r") as fobj:
+            for line in fobj:
+                if line.strip().startswith(versionfile_source):
+                    if "export-subst" in line.strip().split()[1:]:
+                        present = True
+                        break
     except EnvironmentError:
         pass
     if not present:
-        f = open(".gitattributes", "a+")
-        f.write("%s export-subst\n" % versionfile_source)
-        f.close()
+        with open(".gitattributes", "a+") as fobj:
+            fobj.write(f"{versionfile_source} export-subst\n")
         files.append(".gitattributes")
     run_command(GITS, ["add", "--"] + files)
 
@@ -1163,15 +1300,14 @@ def versions_from_parentdir(parentdir_prefix, root, verbose):
     """
     rootdirs = []
 
-    for i in range(3):
+    for _ in range(3):
         dirname = os.path.basename(root)
         if dirname.startswith(parentdir_prefix):
             return {"version": dirname[len(parentdir_prefix):],
                     "full-revisionid": None,
                     "dirty": False, "error": None, "date": None}
-        else:
-            rootdirs.append(root)
-            root = os.path.dirname(root)  # up a level
+        rootdirs.append(root)
+        root = os.path.dirname(root)  # up a level
 
     if verbose:
         print("Tried directories %s but none started with prefix %s" %
@@ -1180,7 +1316,7 @@ def versions_from_parentdir(parentdir_prefix, root, verbose):
 
 
 SHORT_VERSION_PY = """
-# This file was generated by 'versioneer.py' (0.18) from
+# This file was generated by 'versioneer.py' (0.20) from
 # revision-control system data, or from the parent directory name of an
 # unpacked source archive. Distribution tarballs contain a pre-generated copy
 # of this file.
@@ -1257,19 +1393,49 @@ def render_pep440(pieces):
     return rendered
 
 
+def render_pep440_branch(pieces):
+    """TAG[[.dev0]+DISTANCE.gHEX[.dirty]] .
+
+    The ".dev0" means not master branch. Note that .dev0 sorts backwards
+    (a feature branch will appear "older" than the master branch).
+
+    Exceptions:
+    1: no tags. 0[.dev0]+untagged.DISTANCE.gHEX[.dirty]
+    """
+    if pieces["closest-tag"]:
+        rendered = pieces["closest-tag"]
+        if pieces["distance"] or pieces["dirty"]:
+            if pieces["branch"] != "master":
+                rendered += ".dev0"
+            rendered += plus_or_dot(pieces)
+            rendered += "%d.g%s" % (pieces["distance"], pieces["short"])
+            if pieces["dirty"]:
+                rendered += ".dirty"
+    else:
+        # exception #1
+        rendered = "0"
+        if pieces["branch"] != "master":
+            rendered += ".dev0"
+        rendered += "+untagged.%d.g%s" % (pieces["distance"],
+                                          pieces["short"])
+        if pieces["dirty"]:
+            rendered += ".dirty"
+    return rendered
+
+
 def render_pep440_pre(pieces):
-    """TAG[.post.devDISTANCE] -- No -dirty.
+    """TAG[.post0.devDISTANCE] -- No -dirty.
 
     Exceptions:
-    1: no tags. 0.post.devDISTANCE
+    1: no tags. 0.post0.devDISTANCE
     """
     if pieces["closest-tag"]:
         rendered = pieces["closest-tag"]
         if pieces["distance"]:
-            rendered += ".post.dev%d" % pieces["distance"]
+            rendered += ".post0.dev%d" % pieces["distance"]
     else:
         # exception #1
-        rendered = "0.post.dev%d" % pieces["distance"]
+        rendered = "0.post0.dev%d" % pieces["distance"]
     return rendered
 
 
@@ -1300,12 +1466,41 @@ def render_pep440_post(pieces):
     return rendered
 
 
+def render_pep440_post_branch(pieces):
+    """TAG[.postDISTANCE[.dev0]+gHEX[.dirty]] .
+
+    The ".dev0" means not master branch.
+
+    Exceptions:
+    1: no tags. 0.postDISTANCE[.dev0]+gHEX[.dirty]
+    """
+    if pieces["closest-tag"]:
+        rendered = pieces["closest-tag"]
+        if pieces["distance"] or pieces["dirty"]:
+            rendered += ".post%d" % pieces["distance"]
+            if pieces["branch"] != "master":
+                rendered += ".dev0"
+            rendered += plus_or_dot(pieces)
+            rendered += "g%s" % pieces["short"]
+            if pieces["dirty"]:
+                rendered += ".dirty"
+    else:
+        # exception #1
+        rendered = "0.post%d" % pieces["distance"]
+        if pieces["branch"] != "master":
+            rendered += ".dev0"
+        rendered += "+g%s" % pieces["short"]
+        if pieces["dirty"]:
+            rendered += ".dirty"
+    return rendered
+
+
 def render_pep440_old(pieces):
     """TAG[.postDISTANCE[.dev0]] .
 
     The ".dev0" means dirty.
 
-    Eexceptions:
+    Exceptions:
     1: no tags. 0.postDISTANCE[.dev0]
     """
     if pieces["closest-tag"]:
@@ -1376,10 +1571,14 @@ def render(pieces, style):
 
     if style == "pep440":
         rendered = render_pep440(pieces)
+    elif style == "pep440-branch":
+        rendered = render_pep440_branch(pieces)
     elif style == "pep440-pre":
         rendered = render_pep440_pre(pieces)
     elif style == "pep440-post":
         rendered = render_pep440_post(pieces)
+    elif style == "pep440-post-branch":
+        rendered = render_pep440_post_branch(pieces)
     elif style == "pep440-old":
         rendered = render_pep440_old(pieces)
     elif style == "git-describe":
@@ -1479,8 +1678,12 @@ def get_version():
     return get_versions()["version"]
 
 
-def get_cmdclass():
-    """Get the custom setuptools/distutils subclasses used by Versioneer."""
+def get_cmdclass(cmdclass=None):
+    """Get the custom setuptools/distutils subclasses used by Versioneer.
+
+    If the package uses a different cmdclass (e.g. one from numpy), it
+    should be provide as an argument.
+    """
     if "versioneer" in sys.modules:
         del sys.modules["versioneer"]
         # this fixes the "python setup.py develop" case (also 'install' and
@@ -1494,9 +1697,9 @@ def get_cmdclass():
         # parent is protected against the child's "import versioneer". By
         # removing ourselves from sys.modules here, before the child build
         # happens, we protect the child from the parent's versioneer too.
-        # Also see https://github.com/warner/python-versioneer/issues/52
+        # Also see https://github.com/python-versioneer/python-versioneer/issues/52
 
-    cmds = {}
+    cmds = {} if cmdclass is None else cmdclass.copy()
 
     # we add "version" to both distutils and setuptools
     from distutils.core import Command
@@ -1538,7 +1741,9 @@ def run(self):
     #  setup.py egg_info -> ?
 
     # we override different "build_py" commands for both environments
-    if "setuptools" in sys.modules:
+    if 'build_py' in cmds:
+        _build_py = cmds['build_py']
+    elif "setuptools" in sys.modules:
         from setuptools.command.build_py import build_py as _build_py
     else:
         from distutils.command.build_py import build_py as _build_py
@@ -1558,6 +1763,33 @@ def run(self):
                 write_to_version_file(target_versionfile, versions)
     cmds["build_py"] = cmd_build_py
 
+    if 'build_ext' in cmds:
+        _build_ext = cmds['build_ext']
+    elif "setuptools" in sys.modules:
+        from setuptools.command.build_ext import build_ext as _build_ext
+    else:
+        from distutils.command.build_ext import build_ext as _build_ext
+
+    class cmd_build_ext(_build_ext):
+        def run(self):
+            root = get_root()
+            cfg = get_config_from_root(root)
+            versions = get_versions()
+            _build_ext.run(self)
+            if self.inplace:
+                # build_ext --inplace will only build extensions in
+                # build/lib<..> dir with no _version.py to write to.
+                # As in place builds will already have a _version.py
+                # in the module dir, we do not need to write one.
+                return
+            # now locate _version.py in the new build/ directory and replace
+            # it with an updated value
+            target_versionfile = os.path.join(self.build_lib,
+                                              cfg.versionfile_build)
+            print("UPDATING %s" % target_versionfile)
+            write_to_version_file(target_versionfile, versions)
+    cmds["build_ext"] = cmd_build_ext
+
     if "cx_Freeze" in sys.modules:  # cx_freeze enabled?
         from cx_Freeze.dist import build_exe as _build_exe
         # nczeczulin reports that py2exe won't like the pep440-style string
@@ -1591,10 +1823,7 @@ def run(self):
         del cmds["build_py"]
 
     if 'py2exe' in sys.modules:  # py2exe enabled?
-        try:
-            from py2exe.distutils_buildexe import py2exe as _py2exe  # py3
-        except ImportError:
-            from py2exe.build_exe import py2exe as _py2exe  # py2
+        from py2exe.distutils_buildexe import py2exe as _py2exe
 
         class cmd_py2exe(_py2exe):
             def run(self):
@@ -1619,7 +1848,9 @@ def run(self):
         cmds["py2exe"] = cmd_py2exe
 
     # we override different "sdist" commands for both environments
-    if "setuptools" in sys.modules:
+    if 'sdist' in cmds:
+        _sdist = cmds['sdist']
+    elif "setuptools" in sys.modules:
         from setuptools.command.sdist import sdist as _sdist
     else:
         from distutils.command.sdist import sdist as _sdist
@@ -1627,6 +1858,7 @@ def run(self):
     class cmd_sdist(_sdist):
         def run(self):
             versions = get_versions()
+            # pylint:disable=attribute-defined-outside-init # noqa
             self._versioneer_generated_versions = versions
             # unless we update this, the command will keep using the old
             # version
@@ -1686,15 +1918,20 @@ def make_release_tree(self, base_dir, files):
 
 """
 
-INIT_PY_SNIPPET = """
+OLD_SNIPPET = """
 from ._version import get_versions
 __version__ = get_versions()['version']
 del get_versions
 """
 
+INIT_PY_SNIPPET = """
+from . import {0}
+__version__ = {0}.get_versions()['version']
+"""
+
 
 def do_setup():
-    """Main VCS-independent setup function for installing Versioneer."""
+    """Do main VCS-independent setup function for installing Versioneer."""
     root = get_root()
     try:
         cfg = get_config_from_root(root)
@@ -1726,10 +1963,16 @@ def do_setup():
                 old = f.read()
         except EnvironmentError:
             old = ""
-        if INIT_PY_SNIPPET not in old:
+        module = os.path.splitext(os.path.basename(cfg.versionfile_source))[0]
+        snippet = INIT_PY_SNIPPET.format(module)
+        if OLD_SNIPPET in old:
+            print(" replacing boilerplate in %s" % ipy)
+            with open(ipy, "w") as f:
+                f.write(old.replace(OLD_SNIPPET, snippet))
+        elif snippet not in old:
             print(" appending to %s" % ipy)
             with open(ipy, "a") as f:
-                f.write(INIT_PY_SNIPPET)
+                f.write(snippet)
         else:
             print(" %s unmodified" % ipy)
     else:


Test patch: