The following revision refers to this bug:
  https://chromium.googlesource.com/infra/infra/+/f7d08e379bb9e69305813c0e7b55a72cb662964c

commit f7d08e379bb9e69305813c0e7b55a72cb662964c
Author: Roberto Carrillo <robertocn@google.com>
Date: Thu Jun 15 18:36:19 2017

[Findit] Fix race condition in unittests.

The MockTryJob class was created with class attributes instead of
instance attributes. This causes race condition and flakiness in tests.

This change should take care of those conditions by creating an object
with instance attributes.

Also, reenabling the test that was affected.

R=stgao,lijeffrey,chanli
BUG= 732895 

Change-Id: I38d778fa62354264337c30d68629ffecf11262aa
Reviewed-on: https://chromium-review.googlesource.com/533682
Reviewed-by: Chan Li <chanli@chromium.org>
Commit-Queue: Roberto Carrillo <robertocn@chromium.org>

[modify] https://crrev.com/f7d08e379bb9e69305813c0e7b55a72cb662964c/appengine/findit/waterfall/swarming_util.py
[modify] https://crrev.com/f7d08e379bb9e69305813c0e7b55a72cb662964c/appengine/findit/waterfall/test/swarming_util_test.py