In rietveld.filter_latest_jobs, handle jobs with no build number.

third_party/WebKit/Tools/Scripts/webkitpy/common/net/rietveld.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.
 
 """Utility functions to communicate with Rietveld."""
 
 import collections
 import json
 import logging
 import urllib2
@@ skipping 78 matching lines @@
         jobs: A list of Build objects.
 
     Returns:
         A list of Build objects such that only the latest job for each builder
         is kept.
     """
     builder_to_highest_number = {}
     for j in jobs:
         if j.build_number > builder_to_highest_number.get(j.builder_name, 0):
             builder_to_highest_number[j.builder_name] = j.build_number
-    return [j for j in jobs if builder_to_highest_number[j.builder_name] == j.build_number]
+    return [j for j in jobs if (
+        j.builder_name in builder_to_highest_number and
+        builder_to_highest_number[j.builder_name] == j.build_number
+    )]
 
 
 def get_latest_try_job_results(issue_number, web):
     url = _latest_patchset_url(issue_number, web)
     patchset_data = _get_json(url, web)
     results = {}
     for job in patchset_data['try_job_results']:
         results[job['builder']] = job['result']
     return results