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

appengine/findit/waterfall/test/try_job_util_test.py

 # Copyright 2015 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.
 
 from testing_utils import testing
 
 from model import wf_analysis_status
 from model.wf_analysis import WfAnalysis
 from model.wf_try_job import WfTryJob
 from waterfall import try_job_util
@@ skipping 255 matching lines @@
     self.assertEqual(expected_failure_result_map, failure_result_map)
     self.assertEqual(222, last_pass)
     self.assertEqual('test', try_job_type)
     self.assertEqual(expected_targeted_tests, targeted_tests)
 
   def testNeedANewTryJobIfTestFailureSwarming(self):
     master_name = 'm'
     builder_name = 'b'
     build_number = 223
     failed_steps = {
-        'a': {
+        'a on platform': {
             'current_failure': 223,
             'first_failure': 222,
             'last_pass': 221,
             'tests': {
                 'a.t1': {
                     'current_failure': 223,
                     'first_failure': 223,
                     'last_pass': 221
                 },
                 'a.t2': {
@@ skipping 26 matching lines @@
             }
         }
     }
 
     failure_result_map = {}
     need_try_job, last_pass, try_job_type, targeted_tests = (
         try_job_util._NeedANewTryJob(master_name, builder_name, build_number,
                                      failed_steps, failure_result_map))
 
     expected_failure_result_map = {
-        'a': {
+        'a on platform': {
             'a.t1': 'm/b/223',
             'a.t2': 'm/b/222',
             'a.t3': 'm/b/223'
         },
         'b': {
             'b.t1': 'm/b/222',
             'b.t2': 'm/b/222'
         },
     }
 
@@ skipping 53 matching lines @@
         'compile': {
             'failed_targets': [
                 {'target': 'a.exe'},
                 {'source': 'b.cc',
                  'target': 'b.o'}]
         }
     }
 
     self.assertEqual(
         try_job_util._GetFailedTargetsFromSignals(signals), ['a.exe'])