$ git clone -n https://src.fedoraproject.org/rpms/layer-shell-qt.git /var/lib/mock/f42-build-side-1-3569440-46747/root/chroot_tmpdir/scmroot/layer-shell-qt
Cloning into '/var/lib/mock/f42-build-side-1-3569440-46747/root/chroot_tmpdir/scmroot/layer-shell-qt'...
$ git fetch origin 52451cc85a28d8fc3d889a298a0d53e87dc8d69e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/layer-shell-qt
 * [new ref]         52451cc85a28d8fc3d889a298a0d53e87dc8d69e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 52451cc 6.4.0