Some recipes interacting with older revisions (e.g. bisect)
will need this.

Bug: 570091
Change-Id: I38e5ffa2db1a9bfae3667f015f00977c32ebe51e
Reviewed-on: https://chromium-review.googlesource.com/519407
Commit-Queue: Paweł Hajdan Jr. <phajdan.jr@chromium.org>
Reviewed-by: Robbie Iannucci <iannucci@chromium.org>