$ git clone -n https://src.fedoraproject.org/rpms/gtkgreet.git /var/lib/mock/f45-build-13179-447/root/chroot_tmpdir/scmroot/gtkgreet
Cloning into '/var/lib/mock/f45-build-13179-447/root/chroot_tmpdir/scmroot/gtkgreet'...
$ git fetch origin 21c609fca29e7a9e5badc7cdf08523342b482a63:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gtkgreet
 * [new ref]         21c609fca29e7a9e5badc7cdf08523342b482a63 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 21c609f Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild