[Findit] Use step level analysis to exclude flaky test failures.

appengine/findit/waterfall/analyze_build_failure_pipeline.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 datetime import datetime
 
 from model.wf_analysis import WfAnalysis
 from model import wf_analysis_status
 from waterfall.base_pipeline import BasePipeline
 from waterfall.detect_first_failure_pipeline import DetectFirstFailurePipeline
@@ skipping 10 matching lines @@
     self.master_name = master_name
     self.builder_name = builder_name
     self.build_number = build_number
   
   def _LogUnexpectedAborting(self, was_aborted):
     """Marks the WfAnalysis status as error, indicating that it was aborted.
        
     Args:
       was_aborted (bool): True if the pipeline was aborted, otherwise False.
     """
-    if was_aborted:  
+    if was_aborted:
       analysis = WfAnalysis.Get(
           self.master_name, self.builder_name, self.build_number)
       if analysis:  # In case the analysis is deleted manually.
         analysis.status = wf_analysis_status.ERROR
         analysis.result_status = None
         analysis.put()
        
   def finalized(self):
-    self._LogUnexpectedAborting(self.was_aborted)      
+    self._LogUnexpectedAborting(self.was_aborted)
 
   def pipeline_status_path(self):
     """Returns an absolute path to look up the status of the pipeline."""
     return '/_ah/pipeline/status?root=%s&auto=false' % self.root_pipeline_id
 
   def _ResetAnalysis(self, master_name, builder_name, build_number):
     analysis = WfAnalysis.Get(master_name, builder_name, build_number)
     analysis.pipeline_status_path = self.pipeline_status_path()
     analysis.status = wf_analysis_status.ANALYZING
     analysis.result_status = None
     analysis.start_time = datetime.utcnow()
     analysis.put()
 
   # Arguments number differs from overridden method - pylint: disable=W0221
   def run(self, master_name, builder_name, build_number):
     self._ResetAnalysis(master_name, builder_name, build_number)
 
     # The yield statements below return PipelineFutures, which allow subsequent
     # pipelines to refer to previous output values.
     # https://github.com/GoogleCloudPlatform/appengine-pipelines/wiki/Python
     failure_info = yield DetectFirstFailurePipeline(
         master_name, builder_name, build_number)
     change_logs = yield PullChangelogPipeline(failure_info)
     signals = yield ExtractSignalPipeline(failure_info)
     yield IdentifyCulpritPipeline(failure_info, change_logs, signals)