$ git clone -n https://src.fedoraproject.org/rpms/mcjoin.git /var/lib/mock/f45-build-18145-510/root/chroot_tmpdir/scmroot/mcjoin
Cloning into '/var/lib/mock/f45-build-18145-510/root/chroot_tmpdir/scmroot/mcjoin'...
$ git fetch origin 9098151df203d81145d43f27c375cdd4ef210d1e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/mcjoin
 * [new ref]         9098151df203d81145d43f27c375cdd4ef210d1e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9098151 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild