Handle KeyboardInterrupt consistently in python scripts

git_map_branches.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.
 
 """Provides a short mapping of all the branches in your local repo, organized
 by their upstream ('tracking branch') layout.
 
 Example:
 origin/master
@@ skipping 248 matching lines @@
         '.'.join(str(x) for x in MIN_UPSTREAM_TRACK_GIT_VERSION) +
         '. Please consider upgrading.')
 
   parser = argparse.ArgumentParser(
       description='Print a a tree of all branches parented by their upstreams')
   parser.add_argument('-v', action='count',
                       help='Display branch hash and Rietveld URL')
   parser.add_argument('--no-color', action='store_true', dest='nocolor',
                       help='Turn off colors.')
 
-  opts = parser.parse_args(argv[1:])
+  opts = parser.parse_args(argv)
 
   mapper = BranchMapper()
   mapper.verbosity = opts.v
   mapper.output.nocolor = opts.nocolor
   mapper.start()
   print mapper.output.as_formatted_string()
+  return 0
 
 if __name__ == '__main__':
-  sys.exit(main(sys.argv))
+  try:
+    sys.exit(main(sys.argv[1:]))
+  except KeyboardInterrupt:
+    sys.stderr.write('interrupted\n')
+    sys.exit(1)