$ git clone -n https://src.fedoraproject.org/rpms/gdm.git /var/lib/mock/f45-build-9683-407/root/chroot_tmpdir/scmroot/gdm
Cloning into '/var/lib/mock/f45-build-9683-407/root/chroot_tmpdir/scmroot/gdm'...
$ git fetch origin d6b96264374b4f77622502b45cb7d6405cf790aa:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gdm
 * [new ref]         d6b96264374b4f77622502b45cb7d6405cf790aa -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d6b9626 Update to 51.0