Remove support for skipping tests

Summary: Almost revert D2673 but leave the support for 'repeat'.

Test Plan: `arc help unit`.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D2689
Pass for phutil test that was expected to fail and skip

Summary:
I just hope that we will not create `ArcanistPhutilTestCaseTestCaseTestCase`.

Also fix a copy/paste error (@edward's this time).

Test Plan: `arc unit`

Reviewers: epriestley

Reviewed By: epriestley

CC: edward, aran, Korvin

Differential Revision: https://secure.phabricator.com/D2692
Use .^ instead of HEAD^ for mercurial

Summary:
##arc amend## in a mercurial repo was failing with this message

    Usage Exception: Commit 'HEAD^' is not a valid Mercurial commit identifier.

mercurial's .^ is about the same thing as git's HEAD^

Test Plan:
##arc amend## in a mercurial repo with ##"immutable_history" : "false"## in the
##.arcconfig##.

Reviewers: epriestley

Reviewed By: epriestley

CC: vrana, aran, Korvin

Differential Revision: https://secure.phabricator.com/D2690
Merge pull request #36 from phleet/hg-head-pull

Use .^ instead of HEAD^ for mercurial
Use getConfigFromAnySource when checking for immutable_history
Merge pull request #37 from phleet/immutable-history-config-from-any-source

Use getConfigFromAnySource when checking for immutable_history
Fix lint errors found by Nemo

Test Plan: Ran a script analyzing sources by HPHP.

Reviewers: epriestley, jungejason

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D2710
Wrap errors in `arc diff`

Test Plan: Add invalid reviewer in `arc diff`.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D2727
[Arcanist] move scratch directory into the vcs metadata directory

Summary:
Using .arc as the scratch and per-repository configuration directory
has some unfortunate consequenses in the real world.  Among other
things, people forget to .gitignore it so it gets checked in.

Test Plan:
the only thing that seems to use this is the relative commit setting
for git.  This diff consists of 2 commits, one for the .gitignore and
one for everything else.

Comment out the portion of my .git/config that defines the upstream
for the branch.  Run arc diff --only with HEAD^ in
.arc/default-relative-commit.  See that .gitignore is not included in
the resultant diff, that .arc no longer exists, and that .git/arc
exists and has HEAD^ in .git/arc/default-relative-commit.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T1233

Differential Revision: https://secure.phabricator.com/D2725
Include common extensions in symbol mapper

Summary:
Spamming everyone who got bitten by this. We upgraded the libphutil library system recently, but the "use of undeclared function" lint check used to run only on files you touched and now runs on every file in every library you use. This means that if you don't have pcntl or ldap installed, you'll get errors about use of functions from them on every change.

Instead, ship with a list of functions which are provided by extensions that we'll ignore when calculating dependencies, so not having pcntl doesn't mean you have to excuse through irrelevant errrors every time.

Test Plan: Ran script with an unknown function, got it in the map; added it to the extension list, it vanished from the map.

Reviewers: vrana, btrahan, allenjohnashton, ddfisher, keebuhm, phleet, nodren

Reviewed By: vrana

CC: aran

Maniphest Tasks: T1347

Differential Revision: https://secure.phabricator.com/D2728
Merge branch 'master' of http://github.com/facebook/arcanist