$ git clone -n https://src.fedoraproject.org/rpms/solar-backgrounds.git /var/lib/mock/f45-build-36201-702/root/chroot_tmpdir/scmroot/solar-backgrounds
Cloning into '/var/lib/mock/f45-build-36201-702/root/chroot_tmpdir/scmroot/solar-backgrounds'...
$ git fetch origin 4c4ba1b96971d620836d00e180d8c6a8ba10d0f6:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/solar-backgrounds
 * [new ref]         4c4ba1b96971d620836d00e180d8c6a8ba10d0f6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4c4ba1b Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild