Some users get 404s when running 'git cl upload' because gclient attempts
to upload as a reitveld patch.

Change-Id: I8fb5a46480f91489a05fbff918a106312cf0118c
Reviewed-on: https://chromium-review.googlesource.com/301474Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>