[Findit] Strip platform from step_name before triggering try job.

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 143 matching lines @@
                 '--gtest_filter=a.b:a.c'],
             'grace_period_secs': 30,
             'idempotent': False,
             'inputs_ref': {'a': 1},
             'io_timeout_secs': 1200,
         },
         'tags': ['purpose:deflake', 'ref_master:%s' % master_name,
                  'ref_buildername:%s' % builder_name,
                  'ref_buildnumber:%s' % build_number,
                  'ref_stepname:%s' % step_name,
-                 'ref_task_id:1'],
+                 'ref_task_id:1',
+                 'ref_name:%s' % step_name],
         'user': '',
     }
 
     pipeline = TriggerSwarmingTaskPipeline()
     new_task_id = pipeline.run(
         master_name, builder_name, build_number, step_name, tests)
     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'])