$ git clone -n https://src.fedoraproject.org/rpms/xvidcore.git /var/lib/mock/f45-build-39155-732/root/chroot_tmpdir/scmroot/xvidcore
Cloning into '/var/lib/mock/f45-build-39155-732/root/chroot_tmpdir/scmroot/xvidcore'...
$ git fetch origin bb6656f2ef700abf034cacc6e1d11b74af748e60:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/xvidcore
 * [new ref]         bb6656f2ef700abf034cacc6e1d11b74af748e60 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at bb6656f Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild