[pinpoint] Move mann_whitney_u.py to models/

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
 from google.appengine.ext import ndb
 
 from dashboard.common import utils
-from dashboard.pinpoint import mann_whitney_u
 from dashboard.pinpoint.models import attempt as attempt_module
 from dashboard.pinpoint.models import change as change_module
+from dashboard.pinpoint.models import mann_whitney_u
 from dashboard.services import gitiles_service
 from dashboard.services import issue_tracker_service
 
 
 # We want this to be fast to minimize overhead while waiting for tasks to
 # finish, but don't want to consume too many resources.
 _TASK_INTERVAL = 10
 
 
 _DEFAULT_REPEAT_COUNT = 15
@@ skipping 359 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