Handle KeyboardInterrupt consistently in python scripts

git_mark_merge_base.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.
 
 """
 Explicitly set/remove/print the merge-base for the current branch.
 
 This manually set merge base will be a stand-in for `git merge-base` for the
 purposes of the chromium depot_tools git extensions. Passing no arguments will
@@ skipping 21 matching lines @@
   g.add_argument('--delete', '-d', action='store_true',
                  help='Remove the set mark.')
   opts = parser.parse_args(argv)
 
   cur = current_branch()
 
   if opts.delete:
     try:
       remove_merge_base(cur)
     except CalledProcessError:
-      print "No merge base currently exists for %s." % cur
+      print 'No merge base currently exists for %s.' % cur
     return 0
 
   if opts.merge_base:
     try:
       opts.merge_base = hash_one(opts.merge_base)
     except CalledProcessError:
       print >> sys.stderr, (
           'fatal: could not resolve %s as a commit' % (opts.merge_base)
       )
       return 1
 
     manual_merge_base(cur, opts.merge_base, upstream(cur))
 
   ret = 0
   actual = get_or_create_merge_base(cur)
   if opts.merge_base and opts.merge_base != actual:
     ret = 1
     print "Invalid merge_base %s" % opts.merge_base
 
   print "merge_base(%s): %s" % (cur, actual)
-
   return ret
 
 
 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)