cmd/coordinator: don't push Gerrit-internal refs to github
cmd/coordinator: don't push Gerrit-internal refs to github

Change-Id: Ie7b0d97e6450be2e31a61bd2f3556060c07d7255
Reviewed-on: https://go-review.googlesource.com/32315
Reviewed-by: Russ Cox <5ad239cb8a44f659eaaee0aa1ea5b94947abe557@golang.org>

golang/build,golang/build,golang/build,golang/build