The following revision refers to this bug:
  https://chromium.googlesource.com/infra/infra/+/ba9859fd4228cb015238db970a2c381649a90297

commit ba9859fd4228cb015238db970a2c381649a90297
Author: Jeffrey Li <lijeffrey@chromium.org>
Date: Fri Oct 06 22:15:29 2017

[Findit] Flake Analyzer - Always run try jobs if heuristic results are available

This change adds another rule to run try jobs, which are now as follows:
  1. Never run try jobs if there is no suspected flake build.
  2. Always run try jobs if the user requested a specific range to run that
     leads to a suspected build.
  3. Never run try jobs if the stable build before the suspect isn't a full 100%
     passing or failing.
  4. Always run try jobs if heuristic analysis suggests a culprit.
  5. Never run try jobs if there is insufficient confidence in the suspected
     build.

Bug:  759804 
Change-Id: I03b293e10a4c5a656fde2e34fd2458811f6def14
Reviewed-on: https://chromium-review.googlesource.com/703923
Reviewed-by: Brandon Wylie <wylieb@chromium.org>
Commit-Queue: Jeffrey Li <lijeffrey@chromium.org>

[modify] https://crrev.com/ba9859fd4228cb015238db970a2c381649a90297/appengine/findit/waterfall/flake/test/initialize_flake_try_job_pipeline_test.py
[modify] https://crrev.com/ba9859fd4228cb015238db970a2c381649a90297/appengine/findit/waterfall/flake/initialize_flake_try_job_pipeline.py