[Findit] Fix KeyError when no failed targets are extracted.

appengine/findit/waterfall/try_job_util.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.
 
 import logging
 
 from google.appengine.api import modules
 from google.appengine.ext import ndb
 
 from model import wf_analysis_status
@@ skipping 107 matching lines @@
 
 
 def _GetFailedTargetsFromSignals(signals, master_name, builder_name):
   compile_targets = []
 
   if not signals or 'compile' not in signals:
     return compile_targets
 
   strict_regex = waterfall_config.EnableStrictRegexForCompileLinkFailures(
       master_name, builder_name)
-  for source_target in signals['compile']['failed_targets']:
+  for source_target in signals['compile'].get('failed_targets', []):
     # For link failures, we pass the executable targets directly to try-job, and
     # there is no 'source' for link failures.
     # For compile failures, only pass the object files as the compile targets
     # for the bots that we use strict regex to extract such information.
     if not source_target.get('source') or strict_regex:
       compile_targets.append(source_target.get('target'))
 
   return compile_targets
 
 
@@ skipping 46 matching lines @@
               pipeline.pipeline_status_path, try_job_type)
     else:  # pragma: no cover
       logging_str = (
           'Try job was scheduled for build %s, %s, %s: %s because of %s '
           'failure.') % (
               master_name, builder_name, build_number,
               pipeline.pipeline_status_path, try_job_type)
     logging.info(logging_str)
 
   return failure_result_map