$ git clone -n https://src.fedoraproject.org/rpms/signon.git /var/lib/mock/f40-build-2645148-66536/root/chroot_tmpdir/scmroot/signon
Cloning into '/var/lib/mock/f40-build-2645148-66536/root/chroot_tmpdir/scmroot/signon'...
$ git fetch origin bc28fc9a231e363c14b70dc32ad100f7653b2fc8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/signon
 * [new ref]         bc28fc9a231e363c14b70dc32ad100f7653b2fc8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at bc28fc9 Update git snapshot