Warn before uploading more than one commit to Gerrit.

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."""
 
 from distutils.version import LooseVersion
@@ skipping 1476 matching lines @@
   if options.target_branch:
     branch = options.target_branch
 
   change_desc = ChangeDescription(
       options.message or CreateDescriptionFromLog(args))
   if not change_desc.description:
     print "Description is empty; aborting."
     return 1
   if CHANGE_ID not in change_desc.description:
     AddChangeIdToCommitMessage(options, args)
+
+  commits = RunGit(['rev-list', '%s/%s...' % (remote, branch)]).splitlines()
+  if len(commits) > 1:
+    print('WARNING: This will upload %d commits. Run the following command '
+          'to see which commits will be uploaded: ' % len(commits))
+    print('git log %s/%s...' % (remote, branch))
+    print('You can also use `git squash-branch` to squash these into a single'
+          'commit.')
+    ask_for_data('About to upload; enter to confirm.')
+
   if options.reviewers:
     change_desc.update_reviewers(options.reviewers)
 
   receive_options = []
   cc = cl.GetCCList().split(',')
   if options.cc:
     cc.extend(options.cc)
   cc = filter(None, cc)
   if cc:
     receive_options += ['--cc=' + email for email in cc]
@@ skipping 1059 matching lines @@
         ('AppEngine is misbehaving and returned HTTP %d, again. Keep faith '
           'and retry or visit go/isgaeup.\n%s') % (e.code, str(e)))
 
 
 if __name__ == '__main__':
   # These affect sys.stdout so do it outside of main() to simplify mocks in
   # unit testing.
   fix_encoding.fix_encoding()
   colorama.init()
   sys.exit(main(sys.argv[1:]))