Change gcl presubmit to only run commit hooks by default.

gcl.py

 #!/usr/bin/python
 # Copyright (c) 2010 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.
 
 """\
 Wrapper script around Rietveld's upload.py that simplifies working with groups
 of files.
 """
 
 import getpass
+import optparse
 import os
 import random
 import re
 import string
 import subprocess
 import sys
 import tempfile
 import time
 from third_party import upload
 import urllib2
@@ skipping 836 matching lines @@
     change_info.Save()
 
   if desc_file:
     os.remove(desc_file)
   change_info.PrimeLint()
   os.chdir(previous_cwd)
   print "*** Upload does not submit a try; use gcl try to submit a try. ***"
   return 0
 
 
-@need_change
-def CMDpresubmit(change_info):
+@need_change_and_args
+@attrs(usage='[--upload]')
+def CMDpresubmit(change_info, args):
   """Runs presubmit checks on the change.
 
   The actual presubmit code is implemented in presubmit_support.py and looks
   for PRESUBMIT.py files."""
   if not change_info.GetFiles():
-    print "Nothing to presubmit check, changelist is empty."
+    print('Nothing to presubmit check, changelist is empty.')
     return 0
-
-  print "*** Presubmit checks for UPLOAD would report: ***"
-  result = DoPresubmitChecks(change_info, False, False)
-
-  print "\n*** Presubmit checks for COMMIT would report: ***"
-  result &= DoPresubmitChecks(change_info, True, False)
-  return not result
+  parser = optparse.OptionParser()
+  parser.add_option('--upload', action='store_true')
+  options, args = parser.parse_args(args)
+  if args:
+    parser.error('Unrecognized args: %s' % args)
+  if options.upload:
+    print('*** Presubmit checks for UPLOAD would report: ***')
+    return not DoPresubmitChecks(change_info, False, False)
+  else:
+    print('*** Presubmit checks for COMMIT would report: ***')
+    return not DoPresubmitChecks(change_info, True, False)
 
 
 def TryChange(change_info, args, swallow_exception):
   """Create a diff file of change_info and send it to the try server."""
   try:
     import trychange
   except ImportError:
     if swallow_exception:
       return 1
     ErrorExit("You need to install trychange.py to use the try server.")
@@ skipping 477 matching lines @@
     if e.code != 500:
       raise
     print >> sys.stderr, (
         'AppEngine is misbehaving and returned HTTP %d, again. Keep faith '
         'and retry or visit go/isgaeup.\n%s') % (e.code, str(e))
     return 1
 
 
 if __name__ == "__main__":
   sys.exit(main(sys.argv[1:]))