$ git clone -n https://src.fedoraproject.org/rpms/f30-backgrounds.git /var/lib/mock/f45-build-8702-394/root/chroot_tmpdir/scmroot/f30-backgrounds
Cloning into '/var/lib/mock/f45-build-8702-394/root/chroot_tmpdir/scmroot/f30-backgrounds'...
$ git fetch origin 3a99fe7b02c08bdd61773c5c39c5a9a0306a150f:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/f30-backgrounds
 * [new ref]         3a99fe7b02c08bdd61773c5c39c5a9a0306a150f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3a99fe7 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild