$ git clone -n https://src.fedoraproject.org/rpms/host-spawn.git /var/lib/mock/f45-build-20368-570/root/chroot_tmpdir/scmroot/host-spawn
Cloning into '/var/lib/mock/f45-build-20368-570/root/chroot_tmpdir/scmroot/host-spawn'...
$ git fetch origin 788e4bbe2bc37efa29cdcd0c56dbdf30ad8722d4:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/host-spawn
 * [new ref]         788e4bbe2bc37efa29cdcd0c56dbdf30ad8722d4 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 788e4bb Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild