Disable lint cache by default

Summary:
Fixes T2266. Motivation:

  - The lint cache does not always invalidate correctly. Because of the nature of the cache, this is a hard problem (right after "naming things").
    - We already have a fair amount of complexity in trying to invalidate it, and are still discovering new places where it doesn't work (e.g., Windows with "/" vs "\" paths).
    - One invalidation failure is when linter code changes, which seems unresolvable in the general case (e.g., changes to external linters).
  - It's not obvious what's happening when the lint cache causes some kind of issue.
    - Particularly while developing or debugging linters, your changes often won't be reflected in the lint output. Some of this is theoretically tractable but the external linter case probably isn't.
  - When someone reports a problem with the lint cache in IRC or elsewhere, there is essentially never a way for me to fix it. The lint cache can't be debugged effectively without access to a working copy where the problem reproduces.
  - The cache provides limited benefit outside of Facebook's install.

To remedy these issues:

  - Introduce configuration which controls cache usage.
  - Default it off.
  - Print a message when the cache is in use.

(I'd tentatively support removing the cache entirely, but I don't know how @vrana and Facebook feel about that.)

Test Plan: Ran `arc set-config --show`, `arc lint --cache 0`, `arc lint --cache 1`.

Reviewers: vrana, btrahan

Reviewed By: vrana

CC: aran, mbishopim3, nh, edward, wez

Maniphest Tasks: T2266

Differential Revision: https://secure.phabricator.com/D5766
Don't use cache in svn-hook-pre-commit

Test Plan: arc lint

Reviewers: epriestley, wez

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D5779
Make the behavior of "--load-phutil-library" more explicit

Summary:
This flag disables normal libraries to make it easier to test library changes. Print that out explicitly.

Also update `.arcconfig` to use the modern configuration format.

Test Plan: Ran `arc list --trace`, `arc list --load-phutil-library=src --trace`.

Reviewers: zeeg, btrahan, vrana

Reviewed By: btrahan

CC: aran

Differential Revision: https://secure.phabricator.com/D5768
Added missing space between words in messages.

Summary:
During my attept to `arc land master` on `master` branch
I have discovered that error message is missing few spaces between words.

I have added them and used this ugly readonly command:

  pcregrep --include="\.php$" -M -r '(?<!\\n| )("|'"'"')\.\n\s*\1(?!\\n| )' ~/arc/arcanist/src

to detect other instances of this serious bug.

Two more were found.
This time they were probably introduced in order to abide
to the draconian lint rule about number of columns.

Since I want to be a good citizen,
I have added this missing space to the begining of the next line in both cases.
It is an ugly hack, but I think user should not suffer due to missing spaces.

Another solution could be preserving no leading spaces and splitting long lines.
Or just providing excuse to lint.

Test Plan: Ran `arc land master` on `master` branch.

Reviewers: epriestley, vrana

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T3008

Differential Revision: https://secure.phabricator.com/D5827
more reusable nosetest engine

Summary:
The NoseTestEngine class has some usefull code for parsing nosetest, but it assumes a very specific code/test
layout. I've pulled this logic abit apart, which lets me reuse the nose-related parts with my existing
project layout, by having my custom engine just call runTests() with the relevant paths.

Test Plan: Run on a customized project with coverage, see coverage results.

Reviewers: epriestley, roman.barzyczak

Reviewed By: epriestley

CC: seporaitis, aran, Korvin, zeeg

Differential Revision: https://secure.phabricator.com/D5921
Adding arc revert command[]

Summary:
Arc Revert does the following:
1. Git revert
2. Go to the differential of the rev you are reverting and either repoen it or set it to a reverted state
3. File a hipri task to orig author

[Preview] Creating Arc Revert workflow

Porting arc revert from FB4A to phabricator for general usage. This is my first stab,
so totally appreciate feedback and assistance. I'm currently focused
on making this work for git. However, I built out the functions through the GitAPI so this
could be easily extendable to Mercurial later on.

Stuck on the following (help):
1. Creating a task for FB internal. I tried building on top of existing arc listeners
but getting errors on failures to load the TaskCreator (and other) tasks.

2. I'm using a hacky way to grab the diff revision id from the newly created
revert diff. (see line 204) I'm looking for a way to just fetch the diff ID
from arc after the diff is created; is this possible?

Test Plan:
 -

1. Ran arc revert on a www and fbcode diff
2. Confirmed that revert was run on the diffs and a proper diff filed
 -

Reviewers: royw, sdwilsh, nh, epriestley

Reviewed By: epriestley

CC: aran, epriestley, Korvin, pti, keir

Maniphest Tasks: T1751

Differential Revision: https://secure.phabricator.com/D5553
Remove "--allow-empty-message"

Summary: @alex has git 1.7.0.4 which doesn't have this flag. We don't actually need it: we always provide a commit message when calling this method. Remove the flag for compatibility, leaving a note in case we bump into this in the future.

Test Plan: N/A

Reviewers: btrahan, vrana, alex

Reviewed By: alex

CC: aran

Differential Revision: https://secure.phabricator.com/D5926
Arcanist changes related to T2784

Summary: These were in my sandbox, but I forgot about them. Without this things break post D5896. Ref T2784

Test Plan: my sandbox works and soon so shall others

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T2784

Differential Revision: https://secure.phabricator.com/D5929
Lint for PHP 5.3 on Windows

Test Plan: Linted `FileFinder`.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D5972
Implementing prefix and suffix diffing for multi-byte unicode characters.

Summary: Prefix and suffix diffing for multi-byte unicode characters.

Test Plan:
Test diff:
------------------------------------------------------------
diff --git a/test b/test
index 252ad2f..a5bad3b 100644
--- a/test
+++ b/test
@@ -1 +1 @@
-This file contains this and this stuff.
+This file contains žžžž and this stuff.
--------------------------------------------------------------

{F43738}
--------------------------------------------------------------

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin, AnhNhan

Maniphest Tasks: T2379

Differential Revision: https://secure.phabricator.com/D5925
Update PHP compat info

Summary: Also warn against functions not available on Windows at all.

Test Plan: Compared old and new file.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D5975
Allow an unassigned flag to be passed to `arc tasks`

Summary: Returns unassigned tasks

Test Plan: Run `arc tasks`, `arc tasks --unassigned`, make sure I get the correct results

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T3201

Differential Revision: https://secure.phabricator.com/D6009
Use PhutilEditDistanceMatrix in ArcanistDiffUtils

Summary: Replace this old hard-coded implementation with the new vector-based, unicode-capable one.

Test Plan: Ran unit tests. Looked at revisions in Differential, using whitespace modes to bypass cache.

Reviewers: btrahan, Afaque_Hussain

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2379

Differential Revision: https://secure.phabricator.com/D6016
Compute UTF8 string differences correctly, accounting for combining characters

Summary:
@Afaque_Hussain has done a bunch of utf8 work here; combined with PhutilEditDistanceMatrix we can now do utf8 diffs correctly, in a general way, without a significant performance impact.

Use PhutilEditDistanceMatrix and `phutil_utf8v_combined()` to compute accurate diffs for all (or, at least, most) UTF8 text.

The only thing this doesn't handle completely correctly is lines beginning with combining characters. This is messy/expensive to handle and will probably never actually happen, so I'm punting for now. Nothing should actually break.

The utf8 stuff will be slow, but we only pay for it when we need it.

Test Plan:
Ran unit tests. I changed a few unit tests to use a non-combining character (snowman) for clarity, and some results are different now (since we get combining characters right).

{F44064}

Reviewers: btrahan, Afaque_Hussain

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2379

Differential Revision: https://secure.phabricator.com/D6019
Print --conduit-uri in install-certificate instructions

Test Plan:
  $ arc diff # without certificate
  $ arc --conduit-uri=http://phabricator.local/ diff # without certificate

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D6037