Needed for parity with Rietveld two-sided patch application.

BUG=628259
R=agable@chromium.org

Change-Id: I79221f54e89a9291257a71b70cc52acc51167854
Reviewed-on: https://chromium-review.googlesource.com/591047Reviewed-by: Aaron Gable <agable@chromium.org>
Commit-Queue: Sergey Berezin <sergeyberezin@chromium.org>