$ git clone -n https://src.fedoraproject.org/rpms/jctools.git /var/lib/mock/f40-build-2386829-60496/root/chroot_tmpdir/scmroot/jctools
Cloning into '/var/lib/mock/f40-build-2386829-60496/root/chroot_tmpdir/scmroot/jctools'...
$ git fetch origin c3a94b79bad659393c241d27eb90c0499c1dacd5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/jctools
 * [new ref]         c3a94b79bad659393c241d27eb90c0499c1dacd5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c3a94b7 Update to upstream version 4.0.2