Fix a corner case in my_reviews.py's median latency calculation.

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 68 matching lines @@
       return 0
     return sum(self.latencies) / float(len(self.latencies))
 
   @property
   def median_latency(self):
     if not self.latencies:
       return 0
     length = len(self.latencies)
     latencies = sorted(self.latencies)
     if (length & 1) == 0:
-      return (latencies[length/2] + latencies[length/2+1]) / 2.
+      return (latencies[length/2] + latencies[length/2-1]) / 2.
     else:
       return latencies[length/2]
 
   @property
   def percent_done(self):
     if not self.total:
       return 0
     return self.actually_reviewed * 100. / self.total
 
   @property
@@ skipping 252 matching lines @@
     print_reviews(
         options.reviewer,
         options.begin,
         options.end,
         options.instance_url)
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())