Ensure --revision is used when specified

gclient_scm.py

 # Copyright (c) 2009 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.
 
 """Gclient-specific SCM-specific operations."""
 
 import logging
 import os
 import posixpath
 import re
@@ skipping 257 matching lines @@
       # case 1
       if self.IsGitSvn(self.checkout_path) and upstream_branch is not None:
         # Our git-svn branch (upstream_branch) is our upstream
         self._AttemptRebase(upstream_branch, files, verbose=options.verbose,
                             newbase=revision, printed_path=printed_path)
         printed_path = True
       else:
         # Can't find a merge-base since we don't know our upstream. That makes
         # this command VERY likely to produce a rebase failure. For now we
         # assume origin is our upstream since that's what the old behavior was.
-        self._AttemptRebase('origin', files=files, verbose=options.verbose,
-                            printed_path=printed_path)
+        upstream_branch = 'origin'
+        if options.revision:
+          upstream_branch = revision
+        self._AttemptRebase(upstream_branch, files=files,
+                            verbose=options.verbose, printed_path=printed_path)
         printed_path = True
     elif rev_type is 'hash':
       # case 2
       self._AttemptRebase(upstream_branch, files, verbose=options.verbose,
                           newbase=revision, printed_path=printed_path)
       printed_path = True
     elif revision.replace('heads', 'remotes/origin') != upstream_branch:
       # case 4
       new_base = revision.replace('heads', 'remotes/origin')
       if not printed_path:
@@ skipping 525 matching lines @@
       print("\n________ couldn't run \'%s\' in \'%s\':\nThe directory "
             "does not exist."
             % (' '.join(command), path))
       # There's no file list to retrieve.
     else:
       self.RunAndGetFileList(options, command, path, file_list)
 
   def FullUrlForRelativeUrl(self, url):
     # Find the forth '/' and strip from there. A bit hackish.
     return '/'.join(self.url.split('/')[:4]) + url