Validate input dates in my_reviews.py.

my_reviews.py

 #!/usr/bin/env python
 # Copyright (c) 2012 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.
 
 """Get rietveld stats about the review you done, or forgot to do.
 
 Example:
   - my_reviews.py -r me@chromium.org -Q  for stats for last quarter.
 """
@@ skipping 324 matching lines @@
   if args:
     parser.error('Args unsupported')
   if not options.reviewer:
     parser.error('$EMAIL_ADDRESS is not set, please use -r')
   print >> sys.stderr, 'Searching for reviews by %s' % options.reviewer
   if options.last_quarter:
     options.begin = begin
     options.end = end
     print >> sys.stderr, 'Using range %s to %s' % (
         options.begin, options.end)
+
+  # Validate dates.
+  try:
+    to_datetime(options.begin)
+    to_datetime(options.end)
+  except ValueError as e:
+    parser.error('%s: %s - %s' % (e, options.begin, options.end))
+
   if options.count:
     print_count(
         options.reviewer,
         options.begin,
         options.end,
         options.instance_url)
   else:
     print_reviews(
         options.reviewer,
         options.begin,
         options.end,
         options.instance_url)
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())