This is needed to change the api.runtime default to is_luci=True in
https://crrev.com/c/1750109.

R=iannucci@google.com, tandrii@google.com

Bug: 993137
Change-Id: Id52e0a12b9121d590fcb61e275eda8ca903372d1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1751815Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
Commit-Queue: Michael Moss <mmoss@chromium.org>