[Findit] Check the explicit culprit from try-job if it is set.

appengine/findit/waterfall/identify_try_job_culprit_pipeline.py

Index: appengine/findit/waterfall/identify_try_job_culprit_pipeline.py
diff --git a/appengine/findit/waterfall/identify_try_job_culprit_pipeline.py b/appengine/findit/waterfall/identify_try_job_culprit_pipeline.py
index 503f0749f143e5325e32f73c3280d222806220fe..00ae824c9febd28569be5624d692bc6b89db4986 100644
--- a/appengine/findit/waterfall/identify_try_job_culprit_pipeline.py
+++ b/appengine/findit/waterfall/identify_try_job_culprit_pipeline.py
@@ -77,6 +77,9 @@ class IdentifyTryJobCulpritPipeline(BasePipeline):
     if not report:
       return None
 
+    if report.get('culprit'):
+      return report.get('culprit')
+
     return IdentifyTryJobCulpritPipeline._GetFailedRevisionFromResultsDict(
         report.get('result', {}))