We should fail when we fail to update depot_tools instead of continuing
the execution silently. Otherwise, developers might get stuck on a bad
depot_tools revision without knowing.

Change-Id: I0431a24a28a77aca8c66352939a0252c458b3e9d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2208616Reviewed-by: Josip Sokcevic <sokcevic@google.com>
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>