GitLab

It's convenient to be able to specify this for both bots and in
individual test suite exceptions, where it's desired to turn on a
particular feature for all tests that are run on a particular
bot. Detect this situation and merge them into proper comma-sorted
lists.

Bug: 826341
Tbr: jbudorick@chromium.org
Change-Id: I11ff1c498182625dae3cfc5c2f0e5e0b4cc4bc5c
Reviewed-on: https://chromium-review.googlesource.com/1042960Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#555871}