Revert of revert and fix "Now trychange can...

Bug=359292
Original commit: b1391c6a
Revert: 8e5f7d308fde74c52e321587649c16568e4a9644

Original commit comment:

> Now trychange can store patches in a Git repo

> A git patch repo is cloned to .git/git-try/patches-git, if was not
> cloned before. Otherwise, changes are pulled. Then a patch is committed a
> pushed.

> --revision=auto (Git only) is resolved to the revision the diff is genera
> against.

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@261247 0039d316-1c4b-4281-b951-d872f2087c98

scm.py

@@ -140,6 +140,10 @@ class GIT(object):
         results.append(('%s      ' % m.group(1)[0], m.group(2)))
     return results
 
+  @staticmethod
+  def IsWorkTreeDirty(cwd):
+    return GIT.Capture(['status', '-s'], cwd=cwd) != ''
+
   @staticmethod
   def GetEmail(cwd):
     """Retrieves the user email address if known."""
@@ -389,6 +393,17 @@ class GIT(object):
     root = GIT.Capture(['rev-parse', '--show-cdup'], cwd=cwd)
     return os.path.abspath(os.path.join(cwd, root))
 
+  @staticmethod
+  def GetGitDir(cwd):
+    return os.path.abspath(GIT.Capture(['rev-parse', '--git-dir'], cwd=cwd))
+
+  @staticmethod
+  def IsInsideWorkTree(cwd):
+    try:
+      return GIT.Capture(['rev-parse', '--is-inside-work-tree'], cwd=cwd)
+    except (OSError, subprocess2.CalledProcessError):
+      return False
+
   @staticmethod
   def GetGitSvnHeadRev(cwd):
     """Gets the most recently pulled git-svn revision."""

tests/scm_unittest.py

@@ -85,13 +85,16 @@ class GitWrapperTestCase(BaseSCMTestCase):
         'GetCheckoutRoot',
         'GetDifferentFiles',
         'GetEmail',
+        'GetGitDir',
         'GetGitSvnHeadRev',
         'GetPatchName',
         'GetSha1ForSvnRev',
         'GetSVNBranch',
         'GetUpstreamBranch',
         'IsGitSvn',
+        'IsInsideWorkTree',
         'IsValidRevision',
+        'IsWorkTreeDirty',
         'MatchSvnGlob',
         'ParseGitSvnSha1',
         'ShortBranchName',

tests/trychange_unittest.py

@@ -46,10 +46,12 @@ class TryChangeUnittest(TryChangeTestsBase):
   """General trychange.py tests."""
   def testMembersChanged(self):
     members = [
-      'DieWithError', 'EPILOG', 'Escape', 'GIT', 'GetMungedDiff', 'GuessVCS',
+      'DieWithError', 'EPILOG', 'Escape', 'GIT', 'GIT_PATCH_DIR_BASENAME',
+      'GetMungedDiff', 'GuessVCS', 'GIT_BRANCH_FILE',
       'HELP_STRING', 'InvalidScript', 'NoTryServerAccess', 'OptionParser',
       'PrintSuccess',
-      'RunCommand', 'RunGit', 'SCM', 'SVN', 'TryChange', 'USAGE', 'breakpad',
+      'RunCommand', 'RunGit', 'SCM', 'SVN', 'TryChange', 'USAGE', 'contextlib',
+      'breakpad',
       'datetime', 'errno', 'fix_encoding', 'gcl', 'gclient_utils', 'gen_parser',
       'getpass', 'itertools', 'json', 'logging', 'optparse', 'os', 'posixpath',
       're', 'scm', 'shutil', 'subprocess2', 'sys', 'tempfile', 'urllib',