Handle KeyboardInterrupt consistently in python scripts

git_squash_branch.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
 
 from git_common import squash_current_branch
 
 def main(args):
   parser = argparse.ArgumentParser()
   parser.add_argument(
       '-m', '--message', metavar='<msg>', default='git squash commit.',
       help='Use the given <msg> as the first line of the commit message.')
   opts = parser.parse_args(args)
   squash_current_branch(opts.message)
+  return 0
+
 
 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)