Handle KeyboardInterrupt consistently in python scripts

git_upstream_diff.py

 #!/usr/bin/env python
 # Copyright 2014 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.
 
 import argparse
 import sys
 
 import subprocess2
 
@@ skipping 20 matching lines @@
     print 'fatal: No upstream configured for branch \'%s\'' % cur
     return 1
 
   cmd = [git.GIT_EXE, 'diff', '--patience', '-C', '-C']
   if opts.wordwise:
     cmd += ['--word-diff=color', r'--word-diff-regex=(\w+|[^[:space:]])']
   cmd += [git.get_or_create_merge_base(cur, par)]
 
   cmd += extra_args
 
-  subprocess2.check_call(cmd)
+  return subprocess2.check_call(cmd)
 
 
 if __name__ == '__main__':
-  sys.exit(main(sys.argv[1:]))
+  try:
+    sys.exit(main(sys.argv[1:]))
+  except KeyboardInterrupt:
+    sys.stderr.write('interrupted\n')
+    sys.exit(1)