[Findit] Capture and store latest buildbucket response with each query

appengine/findit/waterfall/monitor_try_job_pipeline.py

Index: appengine/findit/waterfall/monitor_try_job_pipeline.py
diff --git a/appengine/findit/waterfall/monitor_try_job_pipeline.py b/appengine/findit/waterfall/monitor_try_job_pipeline.py
index 0584130675192e97cdfaeab86d73b3af3545378f..bb864a71fd8732575b08e38f5bc345756fbf4918 100644
--- a/appengine/findit/waterfall/monitor_try_job_pipeline.py
+++ b/appengine/findit/waterfall/monitor_try_job_pipeline.py
@@ -206,6 +206,7 @@ class MonitorTryJobPipeline(BasePipeline):
     start_time = None
     while True:
       error, build = buildbucket_client.GetTryJobs([try_job_id])[0]
+
       if error:
         if allowed_response_error_times > 0:
           allowed_response_error_times -= 1
@@ -253,4 +254,10 @@ class MonitorTryJobPipeline(BasePipeline):
             'Try job %s timed out after %d hours.' % (
                 try_job_id, timeout_hours))
 
+      # Ensure last_buildbucket_response is always the most recent
+      # whenever available during intermediate queries.
+      if build and build.response:
+        try_job_data.last_buildbucket_response = build.response

[stgao, 2016/08/19 21:44:36]

nit: not update datastore if the current response is the same as last one,
because we want to avoid too many write if possible.

+        try_job_data.put()
+
       time.sleep(pipeline_wait_seconds)  # pragma: no cover