Add --upstream flag to presubmit_support for Git.

presubmit_support.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.
 
 """Enables directory-specific presubmit checks to run at upload and/or commit.
 """
 
 __version__ = '1.8.0'
 
@@ skipping 1440 matching lines @@
   change_scm = scm.determine_scm(options.root)
   files = []
   if args:
     files = ParseFiles(args, options.recursive)
   if change_scm == 'svn':
     change_class = SvnChange
     if not files:
       files = scm.SVN.CaptureStatus([], options.root)
   elif change_scm == 'git':
     change_class = GitChange
-    # TODO(maruel): Get upstream.
+    upstream = options.upstream or None
     if not files:
-      files = scm.GIT.CaptureStatus([], options.root, None)
+      files = scm.GIT.CaptureStatus([], options.root, upstream)
   else:
     logging.info('Doesn\'t seem under source control. Got %d files' % len(args))
     if not files:
       return None, None
     change_class = Change
   return change_class, files
 
 
 class NonexistantCannedCheckFilter(Exception):
   pass
@@ skipping 51 matching lines @@
   parser.add_option("--name", default='no name')
   parser.add_option("--author")
   parser.add_option("--description", default='')
   parser.add_option("--issue", type='int', default=0)
   parser.add_option("--patchset", type='int', default=0)
   parser.add_option("--root", default=os.getcwd(),
                     help="Search for PRESUBMIT.py up to this directory. "
                     "If inherit-review-settings-ok is present in this "
                     "directory, parent directories up to the root file "
                     "system directories will also be searched.")
+  parser.add_option("--upstream",
+                    help="Git only: the base ref or upstream branch against "
+                    "which the diff should be computed.")
   parser.add_option("--default_presubmit")
   parser.add_option("--may_prompt", action='store_true', default=False)
   parser.add_option("--skip_canned", action='append', default=[],
                     help="A list of checks to skip which appear in "
                     "presubmit_canned_checks. Can be provided multiple times "
                     "to skip multiple canned checks.")
   parser.add_option("--rietveld_url", help=optparse.SUPPRESS_HELP)
   parser.add_option("--rietveld_email", help=optparse.SUPPRESS_HELP)
   parser.add_option("--rietveld_password", help=optparse.SUPPRESS_HELP)
   parser.add_option("--rietveld_fetch", action='store_true', default=False,
@@ skipping 99 matching lines @@
   except PresubmitFailure, e:
     print >> sys.stderr, e
     print >> sys.stderr, 'Maybe your depot_tools is out of date?'
     print >> sys.stderr, 'If all fails, contact maruel@'
     return 2
 
 
 if __name__ == '__main__':
   fix_encoding.fix_encoding()
   sys.exit(Main(None))