Revert "Make check for dirty index work."

This reverts commit 931b6c6a.

This was causing our try bots to fail on DEPS changes.

After applying the patch successfully, apply_issue.py tries to run gclient sync to get the updated DEPS, resulting in this error:
src (ERROR)
----------------------------------------
[0:00:00] Started.
----------------------------------------
Error: 
____ src at origin/master
	Your index contains uncommitted changes
	Please commit, stash, or reset.

BUG=413326
TESTED=Manually: https://paste.googleplex.com/6375653263802368

Review URL: https://codereview.chromium.org/563873002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@291932 0039d316-1c4b-4281-b951-d872f2087c98

gclient_scm.py

@@ -612,10 +612,9 @@ class GitWrapper(SCMWrapper):
               return
             else:
               self.Print('Input not recognized')
-        elif re.match("error: Your local changes to (')?.*(')? would be "
-                      "overwritten by merge(.  Aborting)?[:.]\n(.*\n)?Please, "
-                      "commit your changes or stash them before you can "
-                      "merge.\n",
+        elif re.match("error: Your local changes to '.*' would be "
+                      "overwritten by merge.  Aborting.\nPlease, commit your "
+                      "changes or stash them before you can merge.\n",
                       e.stderr):
           if not printed_path:
             self.Print('_____ %s%s' % (self.relpath, rev_str), timestamp=False)
@@ -1022,7 +1021,7 @@ class GitWrapper(SCMWrapper):
                                   % (self.relpath, rev_str))
     try:
       scm.GIT.Capture(['diff-index', '--cached', '--name-status', '-r',
-                       '--ignore-submodules', '--exit-code', 'HEAD', '--'],
+                       '--ignore-submodules', 'HEAD', '--'],
                        cwd=self.checkout_path)
     except subprocess2.CalledProcessError:
       raise gclient_utils.Error('\n____ %s%s\n'

tests/gclient_scm_test.py

@@ -919,14 +919,6 @@ from :3
       return return_value
     return AskForData
 
-  def getCurrentBranch(self):
-    # Returns name of current branch or HEAD for detached HEAD
-    branch = gclient_scm.scm.GIT.Capture(['rev-parse', '--abbrev-ref', 'HEAD'],
-                                          cwd=self.base_path)
-    if branch == 'HEAD':
-      return None
-    return branch
-
   def setUp(self):
     TestCaseUtils.setUp(self)
     unittest.TestCase.setUp(self)
@@ -1208,44 +1200,12 @@ class ManagedGitWrapperTestCase(BaseGitWrapperTestCase):
                  'Fix the conflict and run gclient again.\n'
                  'See \'man git-rebase\' for details.\n')
     self.assertRaisesError(exception, scm.update, options, (), [])
-    # The merge conflict creates a detached head with local changes, so another
-    # scm.update attempt should fail (in a different way) because of that (a
-    # rather roundabout way to test that condition).
     exception = ('\n____ . at refs/remotes/origin/master\n'
                  '\tYou have unstaged changes.\n'
                  '\tPlease commit, stash, or reset.\n')
     self.assertRaisesError(exception, scm.update, options, (), [])
     sys.stdout.close()
 
-  def testUpdateDetachedConflict(self):
-    # Detached head mode should refuse to update when there are local changes
-    # (staged or unstaged).
-    if not self.enabled:
-      return
-    options = self.Options()
-    scm = gclient_scm.CreateSCM(url=self.url, root_dir=self.root_dir,
-                                relpath=self.relpath)
-    scm._Run(['checkout', '-q', 'a7142dc9f0009350b96a11f372b6ea658592aa95'],
-             options)
-    # Make sure it checked out a detached HEAD
-    self.assertEquals(self.getCurrentBranch(), None)
-    file_path = join(self.base_path, 'b')
-    open(file_path, 'w').writelines('conflict\n')
-    # Unstaged
-    # TODO(all): Ick. Gclient should really have exception subclasses or
-    # something, so we can avoid this fragile exception message matching.
-    exception = ('\n____ . at refs/remotes/origin/master\n'
-                 '\tYou have unstaged changes.\n'
-                 '\tPlease commit, stash, or reset.\n')
-    self.assertRaisesError(exception, scm.update, options, (), [])
-    # Staged
-    scm._Run(['add', 'b'], options)
-    exception = ('\n____ . at refs/remotes/origin/master\n'
-                 '\tYour index contains uncommitted changes\n'
-                 '\tPlease commit, stash, or reset.\n')
-    self.assertRaisesError(exception, scm.update, options, (), [])
-    sys.stdout.close()
-
   def testRevinfo(self):
     if not self.enabled:
       return
@@ -1469,6 +1429,14 @@ class UnmanagedGitWrapperTestCase(BaseGitWrapperTestCase):
     # pylint: disable=E1101
     self.assertNotIn(expected, value)
 
+  def getCurrentBranch(self):
+    # Returns name of current branch or HEAD for detached HEAD
+    branch = gclient_scm.scm.GIT.Capture(['rev-parse', '--abbrev-ref', 'HEAD'],
+                                          cwd=self.base_path)
+    if branch == 'HEAD':
+      return None
+    return branch
+
   def testUpdateClone(self):
     if not self.enabled:
       return