Add (another) argument to break git locks in gclient.

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 d3fdc684f58ab796de2284c51ea2f547ba06c85d..00592244c90ab633a05752319e5e4569aacdf28d 100755
--- a/tests/gclient_scm_test.py
+++ b/tests/gclient_scm_test.py
@@ -133,6 +133,7 @@ class BaseGitWrapperTestCase(GCBaseTestCase, StdoutCheck, TestCaseUtils,
       self.cache_dir = None
       self.merge = False
       self.jobs = 1
+      self.break_repo_locks = False
       self.delete_unversioned_trees = False
 
   sample_git_import = """blob
@@ -501,6 +502,36 @@ class ManagedGitWrapperTestCase(BaseGitWrapperTestCase):
     sys.stdout.getvalue()
     sys.stdout.close()
 
+  def testUpdateLocked(self):
+    if not self.enabled:
+      return
+    options = self.Options()
+    scm = gclient_scm.CreateSCM(url=self.url, root_dir=self.root_dir,
+                                relpath=self.relpath)
+    file_path = join(self.base_path, '.git', 'index.lock')
+    with open(file_path, 'w'):
+      pass
+    with self.assertRaisesRegexp(subprocess2.CalledProcessError,
+                                 'Unable to create.*/index.lock'):
+      scm.update(options, (), [])
+    sys.stdout.close()
+
+  def testUpdateLockedBreak(self):
+    if not self.enabled:
+      return
+    options = self.Options()
+    options.break_repo_locks = True
+    scm = gclient_scm.CreateSCM(url=self.url, root_dir=self.root_dir,
+                                relpath=self.relpath)
+    file_path = join(self.base_path, '.git', 'index.lock')
+    with open(file_path, 'w'):
+      pass
+    scm.update(options, (), [])
+    self.assertRegexpMatches(sys.stdout.getvalue(),
+                             "breaking lock.*\.git/index\.lock")
+    self.assertFalse(os.path.exists(file_path))
+    sys.stdout.close()
+
   def testUpdateConflict(self):
     if not self.enabled:
       return
@@ -542,6 +573,7 @@ class ManagedGitWrapperTestCaseMox(BaseTestCase):
       self.force = force
       self.reset = False
       self.nohooks = False
+      self.break_repo_locks = False
       # TODO(maruel): Test --jobs > 1.
       self.jobs = 1