The following revision refers to this bug:
  https://chromium.googlesource.com/infra/infra/+/98b78bf003e902e49e5f01c0423b03013a0cdc27

commit 98b78bf003e902e49e5f01c0423b03013a0cdc27
Author: Jeffrey Li <lijeffrey@chromium.org>
Date: Fri Oct 12 00:27:50 2018

[Findit] Implementing function to get latest indexed isolate target

It's not possible to pass float('inf') as a commit position to get the
latest isolate target. Instead, just exclude commit position from the
parameters.

Bug:  894633 
Change-Id: If7f4c92056c29b70d2518c57462d0dfabd771ce1
Reviewed-on: https://chromium-review.googlesource.com/c/1278188
Commit-Queue: Jeffrey Li <lijeffrey@chromium.org>
Reviewed-by: Roberto Carrillo <robertocn@chromium.org>
Cr-Commit-Position: refs/heads/master@{#18267}
[modify] https://crrev.com/98b78bf003e902e49e5f01c0423b03013a0cdc27/appengine/findit/waterfall/build_util.py
[modify] https://crrev.com/98b78bf003e902e49e5f01c0423b03013a0cdc27/appengine/findit/waterfall/test/build_util_test.py
[modify] https://crrev.com/98b78bf003e902e49e5f01c0423b03013a0cdc27/appengine/findit/model/test/isolated_target_test.py
[modify] https://crrev.com/98b78bf003e902e49e5f01c0423b03013a0cdc27/appengine/findit/model/isolated_target.py