$ git clone -n https://src.fedoraproject.org/rpms/layer-shell-qt.git /var/lib/mock/f42-build-side-1-3583036-46887/root/chroot_tmpdir/scmroot/layer-shell-qt
Cloning into '/var/lib/mock/f42-build-side-1-3583036-46887/root/chroot_tmpdir/scmroot/layer-shell-qt'...
$ git fetch origin bcdf9983948b411e4548acc12e89ddc38a17f55b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/layer-shell-qt
 * [new ref]         bcdf9983948b411e4548acc12e89ddc38a17f55b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at bcdf998 6.4.2