remote.c: add command line option parser for "--force-with-lease"

Update "git push" and "git send-pack" to parse this commnd line
option.

The intended sematics is:

 * "--force-with-lease" alone, without specifying the details, will
   protect _all_ remote refs that are going to be updated by
   requiring their current value to be the same as some reasonable
   default, unless otherwise specified;

 * "--force-with-lease=refname", without specifying the expected
   value, will protect that refname, if it is going to be updated,
   by requiring its current value to be the same as some reasonable
   default.

 * "--force-with-lease=refname:value" will protect that refname, if
   it is going to be updated, by requiring its current value to be
   the same as the specified value; and

 * "--no-force-with-lease" will cancel all the previous --force-with-lease on the
   command line.

For now, "some reasonable default" is tentatively defined as "the
value of the remote-tracking branch we have for the ref of the
remote being updated", and it is an error if we do not have such a
remote-tracking branch.  But this is known to be fragile, its use is
not yet recommended, and hopefully we will find more reasonable
default as we gain experience with this feature.  The manual marks
the feature as experimental unless the expected value is specified
explicitly for this reason.

Because the command line options are parsed _before_ we know which
remote we are pushing to, there needs further processing to the
parsed data after we instantiate the transport object to:

 * expand "refname" given by the user to a full refname to be
   matched with the list of "struct ref" used in match_push_refs()
   and set_ref_status_for_push(); and

 * learning the actual local ref that is the remote-tracking branch
   for the specified remote ref.

Further, some processing need to be deferred until we find the set
of remote refs and match_push_refs() returns in order to find the
ones that need to be checked after explicit ones have been processed
for "--force-with-lease" (no specific details).

These post-processing will be the topic of the next patch.

This option was originally called "cas" (for "compare and swap"),
the name which nobody liked because it was too technical.  The
second attempt called it "lockref" (because it is conceptually like
pushing after taking a lock) but the word "lock" was hated because
it implied that it may reject push by others, which is not the way
this option works.  This round calls it "force-with-lease".  You
assume you took the lease on the ref when you fetched to decide what
the rebased history should be, and you can push back only if the
lease has not been broken.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
push --force-with-lease: implement logic to populate old_sha1_expect[]

This plugs the push_cas_option data collected by the command line
option parser to the transport system with a new function
apply_push_cas(), which is called after match_push_refs() has
already been called.

At this point, we know which remote we are talking to, and what
remote refs we are going to update, so we can fill in the details
that may have been missing from the command line, such as

 (1) what abbreviated refname the user gave us matches the actual
     refname at the remote; and

 (2) which remote-tracking branch in our local repository to read
     the value of the object to expect at the remote.

to populate the old_sha1_expect[] field of each of the remote ref.
As stated in the documentation, the use of remote-tracking branch
as the default is a tentative one, and we may come up with a better
logic as we gain experience.

Still nobody uses this information, which is the topic of the next
patch.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
push --force-with-lease: tie it all together

This teaches the deepest part of the callchain for "git push" (and
"git send-pack") to enforce "the old value of the ref must be this,
otherwise fail this push" (aka "compare-and-swap" / "--lockref").

Signed-off-by: Junio C Hamano <gitster@pobox.com>
t5533: test "push --force-with-lease"

Prepare two repositories, src and dst, the latter of which is a
clone of the former (with tracking branches), and push from the
latter into the former, with various --force-with-lease options.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
Merge branch 'jk/fast-import-empty-ls' into jch

* jk/fast-import-empty-ls:
  fast-import: allow moving the root tree
  fast-import: allow ls or filecopy of the root tree
  fast-import: set valid mode on root tree in "ls"
  t9300: document fast-import empty path issues
Merge branch 'nd/magic-pathspec' into jch

Use "struct pathspec" interface in more places, instead of array of
characters, the latter of which cannot express magic pathspecs
(e.g. ":(icase)makefile" that matches both Makefile and makefile).

* nd/magic-pathspec: (47 commits)
  t6131 - skip tests if on case-insensitive file system
  parse_pathspec: accept :(icase)path syntax
  pathspec: support :(glob) syntax
  pathspec: make --literal-pathspecs disable pathspec magic
  pathspec: support :(literal) syntax for noglob pathspec
  kill limit_pathspec_to_literal() as it's only used by parse_pathspec()
  parse_pathspec: preserve prefix length via PATHSPEC_PREFIX_ORIGIN
  parse_pathspec: make sure the prefix part is wildcard-free
  rename field "raw" to "_raw" in struct pathspec
  tree-diff: remove the use of pathspec's raw[] in follow-rename codepath
  remove match_pathspec() in favor of match_pathspec_depth()
  remove init_pathspec() in favor of parse_pathspec()
  remove diff_tree_{setup,release}_paths
  convert common_prefix() to use struct pathspec
  convert add_files_to_cache to take struct pathspec
  convert {read,fill}_directory to take struct pathspec
  convert refresh_index to take struct pathspec
  convert report_path_error to take struct pathspec
  checkout: convert read_tree_some to take struct pathspec
  convert unmerge_cache to take struct pathspec
  ...

# Conflicts:
# 	builtin/clean.c
# 	builtin/ls-files.c
# 	builtin/rm.c
# 	cache.h
# 	pathspec.c
# 	resolve-undo.c
Merge branch 'ob/typofixes' into jch

* ob/typofixes:
  typofix: in-code comments
  typofix: documentation
  typofix: release notes
Merge branch 'mh/multimail' into jch

An enhanced "post-receive" hook to send e-mail messages.

I tend to agree that the wording of the tip one is a bit too
strong.  An old script does not necessarily have to be avoided by
its existing users only because it has not got updates for a long
time.

* mh/multimail:
  post-receive-email: deprecate script in favor of git-multimail
  git-multimail: an improved replacement for post-receive-email
### match next
Merge branch 'km/http-curl-config-per-url' into jch

Allows custom curl configuration per URL when talking over http.

* km/http-curl-config-per-url:
  config: allow http.<url>.* any user matching
  tests: add new test for the url_normalize function
  config: improve support for http.<url>.* settings
  config: add support for http.<url>.* settings
  http.c: fix parsing of http.sslCertPasswordProtected variable
Merge branch 'jc/push-cas' into jch

Allow a safer "rewind of the remote tip" push than blind "--force",
by requiring that the overwritten remote ref to be unchanged since
the new history to replace it was prepared.

The machinery is more or less ready.  The "--force" option is again
the big red button to override any safety, thanks to J6t's sanity
(the original round allowed --lockref to defeat --force).

I have strong doubts on the merit of the logic to choose the
default for "--lockref" implemented here.  It is suitable only for
the simplest workflows, and it may hurt users more than it helps
them.

Also the option may be called something with "--force" prefix, as
it is a weaker and more controlled form of "--force" that is used
to defeat the usual "must fast-forward" safety.

Will redo one more time.

* jc/push-cas:
  t5533: test "push --force-with-lease"
  push --force-with-lease: tie it all together
  push --force-with-lease: implement logic to populate old_sha1_expect[]
  remote.c: add command line option parser for "--force-with-lease"
  builtin/push.c: use OPT_BOOL, not OPT_BOOLEAN
  cache.h: move remote/connect API out of it

# Conflicts:
# 	remote.c
### 2.0
Merge branch 'jc/push-2.0-default-to-simple' into jch

* jc/push-2.0-default-to-simple:
  push: switch default from "matching" to "simple"

# Conflicts:
# 	Documentation/config.txt
# 	Documentation/git-push.txt
# 	builtin/push.c
Merge branch 'jn/add-2.0-u-A-sans-pathspec' into jch

* jn/add-2.0-u-A-sans-pathspec:
  git add: -u/-A now affects the entire working tree

# Conflicts:
# 	builtin/add.c
Merge branch 'jc/add-2.0-ignore-removal' into jch

Updated endgame for "git add <pathspec>" that defaults to "--all"
aka "--no-ignore-removal".

* jc/add-2.0-ignore-removal:
  git add <pathspec>... defaults to "-A"

# Conflicts:
# 	builtin/add.c
Merge branch 'jc/core-checkstat-2.0' into jch

* jc/core-checkstat-2.0:
  core.statinfo: remove as promised in Git 2.0
Merge branch 'jc/hold-diff-remove-q-synonym-for-no-deletion' into jch

* jc/hold-diff-remove-q-synonym-for-no-deletion:
  diff: remove "diff-files -q" in a version of Git in a distant future

# Conflicts:
# 	diff.c
Merge branch 'mh/packed-refs-do-one-ref-recursion' into pu

* mh/packed-refs-do-one-ref-recursion:
  do_one_ref(): save and restore value of current_ref
Merge branch 'jc/reflog-doc' into pu

Document rules to use GIT_REFLOG_ACTION variable in the scripted
Porcelain.  git-rebase--interactive locally violates this, but it
is a leaf user that does not call out to or dot-sources other
scripts, so fixing it is not all that urgent.

* jc/reflog-doc:
  setup_reflog_action: document the rules for using GIT_REFLOG_ACTION

# Conflicts:
# 	Documentation/git.txt
Merge branch 'tf/gitweb-ss-tweak' into pu

Comments?

* tf/gitweb-ss-tweak:
  gitweb: make search help link less ugly
  gitweb: omit the repository owner when it is unset
  gitweb: vertically centre contents of page footer
  gitweb: ensure OPML text fits inside its box