[Findit] Display last build bucket response to try job dashboard

appengine/findit/waterfall/monitor_try_job_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
 import json
 import time
 
 from google.appengine.ext import ndb
 
@@ skipping 44 matching lines @@
             'message': 'Try job monitoring was abandoned.',
             'reason': 'Timeout after %s hours' % (
                 waterfall_config.GetTryJobSettings().get('job_timeout_hours'))
         },
         try_job_error.TIMEOUT)
 
   if buildbucket_response:
     # Check buildbucket_response.
     buildbucket_failure_reason = buildbucket_response.get('failure_reason')
     if buildbucket_failure_reason == 'BUILD_FAILURE':
-      # Can occurr if an exception is thrown or the disk is full.
+      # Generic buildbucket-reported error which can occurr if an exception is
+      # thrown, disk is full, compile fails during a test try job, etc.
       return (
           {
-              'message': 'Compile failed unexpectedly.',
+              'message': 'Buildbucket reported a general error.',
               'reason': MonitorTryJobPipeline.UNKNOWN
           },
           try_job_error.INFRA_FAILURE
       )
     elif buildbucket_failure_reason == 'INFRA_FAILURE':
       return (
           {
               'message': ('Try job encountered an infra issue during '
                           'execution.'),
               'reason': MonitorTryJobPipeline.UNKNOWN
@@ skipping 167 matching lines @@
           already_set_started = True
 
       if time.time() > deadline:  # pragma: no cover
         _UpdateTryJobMetadata(try_job_data, start_time, build, error, True)
         # Explicitly abort the whole pipeline.
         raise pipeline.Abort(
             'Try job %s timed out after %d hours.' % (
                 try_job_id, timeout_hours))
 
       time.sleep(pipeline_wait_seconds)  # pragma: no cover