Arbitrary refs (i.e. syncing to refs/arbitrary/stuff:revision) is not
guaranteed to work.

Bug: 874501, 942229
Change-Id: If08f0d9ae257e3d9f486d3ea6b310c8d94d3b918
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1542588Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
Reviewed-by: Karen Qian <karenqian@google.com>
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>