[Findit] Fix bug when displaying try job result for swamring tests.

appengine/findit/waterfall/test/trigger_swarming_task_pipeline_test.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 time
 
 from testing_utils import testing
 
 from model import wf_analysis_status
 from model.wf_swarming_task import WfSwarmingTask
@@ skipping 161 matching lines @@
     self.assertEqual('new_task_id', new_task_id)
     self.assertEqual(expected_new_request_json, new_request_json)
 
     swarming_task = WfSwarmingTask.Get(
         master_name, builder_name, build_number, step_name)
     self.assertIsNotNone(swarming_task)
     self.assertEqual('new_task_id', swarming_task.task_id)
     self.assertEqual(tests, swarming_task.parameters['tests'])
     self.assertEqual(_MOCK_SWARMING_SETTINGS['iterations_to_rerun'],
                      swarming_task.parameters['iterations_to_rerun'])
+    self.assertEqual('a_tests', swarming_task.parameters['ref_name'])