It's not used and causes some problems if refs on clone aren't set
properly.

R=ehmaldonado@chromium.org

Bug: 1049610
Change-Id: I71c1215c9a3355dd54e2d66860d755c6fe8032db
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2224853Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
Commit-Queue: Josip Sokcevic <sokcevic@google.com>