[pinpoint] Don't include list of differences in bug post on error.

dashboard/dashboard/pinpoint/models/job.py

 # Copyright 2016 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 collections
 import logging
 import os
 import traceback
 
 from google.appengine.api import taskqueue
@@ skipping 100 matching lines @@
 
   def Start(self):
     self.Schedule()
     self._PostBugComment('started', send_email=False)
 
   def Complete(self):
     self._PostBugComment('completed', include_differences=True)
 
   def Fail(self):
     self.exception = traceback.format_exc()
-    self._PostBugComment('stopped with an error', include_differences=True)
+    self._PostBugComment('stopped with an error')
 
   def Schedule(self):
     task = taskqueue.add(queue_name='job-queue', url='/api/run/' + self.job_id,
                          countdown=_TASK_INTERVAL)
     self.task = task.name
 
   def Run(self):
     self.exception = None  # In case the Job succeeds on retry.
     self.task = None  # In case an exception is thrown.
 
@@ skipping 254 matching lines @@
 
   try:
     p_value = mann_whitney_u.MannWhitneyU(values_a, values_b)
   except ValueError:
     return _UNKNOWN
 
   if p_value < _SIGNIFICANCE_LEVEL:
     return _DIFFERENT
   else:
     return _UNKNOWN