$ git clone -n https://src.fedoraproject.org/rpms/mum-hash.git /var/lib/mock/f45-build-19329-547/root/chroot_tmpdir/scmroot/mum-hash
Cloning into '/var/lib/mock/f45-build-19329-547/root/chroot_tmpdir/scmroot/mum-hash'...
$ git fetch origin 1a23f337bfd0240bc5a864f4c4446ee34cf48970:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/mum-hash
 * [new ref]         1a23f337bfd0240bc5a864f4c4446ee34cf48970 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 1a23f33 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild