Make my_activity.py robust to log parsing problems

my_activity.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 stats about your activity.
 
 Example:
   - my_activity.py  for stats for the current week (last week on mondays).
   - my_activity.py -Q  for stats for last quarter.
@@ skipping 555 matching lines @@
     for query in search:
       query_args = [query]
       query_args.extend(log_args)
       commits |= set(self.git_cmd(repo, 'log', 'origin/master', *query_args))
 
     ret = []
     for commit in commits:
       output = self.git_cmd(repo, 'log', commit + "^!", "--format=%cn%n%cd%n%B")
       author = output[0]
       date = datetime.strptime(output[1], "%a %b %d %H:%M:%S %Y +0000")
-      ret.append(self.process_git_commit(instance, author, date, output[2:]))
+      processed = self.process_git_commit(instance, author, date, output[2:])
+      if processed:
+        ret.append(processed)
 
     ret = sorted(ret, key=lambda i: i['modified'], reverse=True)
     return ret
 
   @staticmethod
   def process_git_commit(instance, author, date, log):
     ret = {}
     ret['owner'] = author
     ret['author'] = author
     ret['modified'] = date
@@ skipping 20 matching lines @@
     committer_list = webkitpy.common.config.committers.CommitterList()
     ret['reviewers'] = set(
         (committer_list.contributor_by_name(r).emails[0] for r in reviewers))
 
     # Reviews more useful than change link itself, but tricky if multiple
     # Reviews == bugs for WebKit changes
     if len(reviews) == 1:
       url = 'http://%s/%d' % (instance['review_url'], reviews[0])
       if instance['review_prop']:
         ret[instance['review_prop']] = reviews[0]
+    elif len(changes) == 1:
+      url = 'http://%s/%d' % (instance['change_url'], changes[0])
     else:
-      url = 'http://%s/%d' % (instance['change_url'], changes[0])
+      # Couldn't find anything.
+      return None
     ret['review_url'] = url
 
     return ret
 
   def bugzilla_issues(self, instance, user):
     if instance['user_func']:
       user = instance['user_func'](user)
     if not user:
       return []
 
@@ skipping 386 matching lines @@
   print '\n\n\n'
 
   my_activity.print_changes()
   my_activity.print_reviews()
   my_activity.print_issues()
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())