$ git clone -n https://src.fedoraproject.org/rpms/gtk-xfce-engine.git /var/lib/mock/f45-build-13191-447/root/chroot_tmpdir/scmroot/gtk-xfce-engine
Cloning into '/var/lib/mock/f45-build-13191-447/root/chroot_tmpdir/scmroot/gtk-xfce-engine'...
$ git fetch origin 378935d3a957f403e7238b827b13b278ce3de949:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gtk-xfce-engine
 * [new ref]         378935d3a957f403e7238b827b13b278ce3de949 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 378935d Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild