$ git clone -n https://src.fedoraproject.org/rpms/f22-backgrounds.git /var/lib/mock/f45-build-8661-393/root/chroot_tmpdir/scmroot/f22-backgrounds
Cloning into '/var/lib/mock/f45-build-8661-393/root/chroot_tmpdir/scmroot/f22-backgrounds'...
$ git fetch origin 2190ff4004c634078440c119a1bccc7857e1cdfa:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/f22-backgrounds
 * [new ref]         2190ff4004c634078440c119a1bccc7857e1cdfa -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2190ff4 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild