--bypass-hooks should bypass all checks, including descriptions 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 1236 matching lines @@
         'GitClHooksBypassedCommit',
         'Issue %s/%s bypassed hook when committing' %
         (cl.GetRietveldServer(), cl.GetIssue()),
         verbose=False)
 
   description = options.message
   if not description and cl.GetIssue():
     description = cl.GetDescription()
 
   if not description:
-    print 'No description set.'
-    print 'Visit %s/edit to set it.' % (cl.GetIssueURL())
-    return 1
+    if not cl.GetIssue() and options.bypass_hooks:
+      description = CreateDescriptionFromLog([base_branch])
+    else:
+      print 'No description set.'
+      print 'Visit %s/edit to set it.' % (cl.GetIssueURL())
+      return 1
 
   if cl.GetIssue():
     description += "\n\nReview URL: %s" % cl.GetIssueURL()
 
   if options.contributor:
     description += "\nPatch from %s." % options.contributor
   print 'Description:', repr(description)
 
   branches = [base_branch, cl.GetBranchRef()]
   if not options.force:
@@ skipping 341 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:]))