Handle KeyboardInterrupt consistently in python scripts

git_freezer.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 sys
 import optparse
 
 import subcommand
 
 from git_common import freeze, thaw
 
 def CMDfreeze(parser, args):
   """Freeze a branch's changes."""
   parser.parse_args(args)
   return freeze()
 
 
 def CMDthaw(parser, args):
   """Returns a frozen branch to the state before it was frozen."""
   parser.parse_args(args)
   return thaw()
 
 
-def main():
+def main(args):
   dispatcher = subcommand.CommandDispatcher(__name__)
-  ret = dispatcher.execute(optparse.OptionParser(), sys.argv[1:])
+  ret = dispatcher.execute(optparse.OptionParser(), args)
   if ret:
     print ret
+  return 0
 
 
 if __name__ == '__main__':
-  main()
+  try:
+    sys.exit(main(sys.argv[1:]))
+  except KeyboardInterrupt:
+    sys.stderr.write('interrupted\n')
+    sys.exit(1)