$ git clone -n https://src.fedoraproject.org/rpms/mcstrans.git /var/lib/mock/f41-build-813677-148784/root/chroot_tmpdir/scmroot/mcstrans
Cloning into '/var/lib/mock/f41-build-813677-148784/root/chroot_tmpdir/scmroot/mcstrans'...
$ git fetch origin b1d98a1233b487555b04a81d08899004d55e8149:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/mcstrans
 * [new ref]         b1d98a1233b487555b04a81d08899004d55e8149 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b1d98a1 Move changelog to changelog and use %autochangelog