Recent changes to luci/client-py contain functionality improvement/fixes to
swarming.py. This is needed by v8 recipes to dispatch swarming tasks.

Bug: chromium:934482
Change-Id: Icdbf213918f10d5bc67d6ce078179e95888281e5
Reviewed-on: https://chromium-review.googlesource.com/c/1480920Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
Commit-Queue: Erik Chen <erikchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59784}