$ git clone -n https://src.fedoraproject.org/rpms/golang-github-prometheus.git /var/lib/mock/f40-build-2239691-53620/root/chroot_tmpdir/scmroot/golang-github-prometheus
Cloning into '/var/lib/mock/f40-build-2239691-53620/root/chroot_tmpdir/scmroot/golang-github-prometheus'...
$ git fetch origin 7c79de4d9546e86b09e04e1a8dcfe2c37a7ae7c2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/golang-github-prometheus
 * [new ref]         7c79de4d9546e86b09e04e1a8dcfe2c37a7ae7c2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 7c79de4 Remove deprecated %patchN syntax