rebaseline-cl: Only support local branches, drop Rietveld support.

third_party/WebKit/Tools/Scripts/webkitpy/common/checkout/git_mock.py

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 from webkitpy.common.system.filesystem_mock import MockFileSystem
 from webkitpy.common.system.executive_mock import MockExecutive
 
 
 class MockGit(object):
 
@@ skipping 89 matching lines @@
         if not self._filesystem:
             return
         for path in paths:
             if self._filesystem.exists(path):
                 self._filesystem.remove(path)
 
     def move(self, origin, destination):
         if self._filesystem:
             self._filesystem.move(self.absolute_path(origin), self.absolute_path(destination))
 
-    def changed_files(self):
+    def changed_files(self, diff_filter='ADM'):
         return []
 
     def unstaged_changes(self):
         return {}