$ git clone -n https://src.fedoraproject.org/rpms/golang-uber-mock.git /var/lib/mock/f40-build-752688-116820/root/chroot_tmpdir/scmroot/golang-uber-mock
Cloning into '/var/lib/mock/f40-build-752688-116820/root/chroot_tmpdir/scmroot/golang-uber-mock'...
$ git fetch origin c151c9db5a304bd79c8f3538a18d554caef9a069:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/golang-uber-mock
 * [new ref]         c151c9db5a304bd79c8f3538a18d554caef9a069 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c151c9d Initial package - Closes rhbz#2223773