Create CachingRietveld to automatically cache results for presubmit checks.

git_cl.py

 #!/usr/bin/env python
 # Copyright (c) 2012 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.
 
 # Copyright (C) 2008 Evan Martin <martine@danga.com>
 
 """A git-command for integrating reviews on Rietveld."""
 
 import json
@@ skipping 724 matching lines @@
       if e.code == 403:
         DieWithError(
             ('Access denied to issue %s. Maybe the patchset %s doesn\'t '
              'match?') % (self.GetIssue(), self.GetPatchset()))
       raise
 
   def RpcServer(self):
     """Returns an upload.RpcServer() to access this review's rietveld instance.
     """
     if not self._rpc_server:
-      self._rpc_server = rietveld.Rietveld(self.GetRietveldServer(),
-                                           None, None)
+      self._rpc_server = rietveld.CachingRietveld(
+          self.GetRietveldServer(), None, None)
     return self._rpc_server
 
   def _IssueSetting(self):
     """Return the git setting that stores this change's issue."""
     return 'branch.%s.rietveldissue' % self.GetBranch()
 
   def _PatchsetSetting(self):
     """Return the git setting that stores this change's most recent patchset."""
     return 'branch.%s.rietveldpatchset' % self.GetBranch()
 
@@ skipping 1105 matching lines @@
              'and retry or visit go/isgaeup.\n%s') % (e.code, str(e)))
 
   # Not a known command. Default to help.
   GenUsage(parser, 'help')
   return CMDhelp(parser, argv)
 
 
 if __name__ == '__main__':
   fix_encoding.fix_encoding()
   sys.exit(main(sys.argv[1:]))