Make check for dirty index work.

tests/gclient_scm_test.py

Index: tests/gclient_scm_test.py
diff --git a/tests/gclient_scm_test.py b/tests/gclient_scm_test.py
index 163cc07457858af1a7c420e9cf2daf410f9370ce..a14ae35ca0e440982701f2cfa38eaf148849ded0 100755
--- a/tests/gclient_scm_test.py
+++ b/tests/gclient_scm_test.py
@@ -919,6 +919,14 @@ 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)
@@ -1200,12 +1208,44 @@ 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
@@ -1429,14 +1469,6 @@ 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