$ git clone -n https://src.fedoraproject.org/rpms/xarchiver.git /var/lib/mock/f40-build-804720-144599/root/chroot_tmpdir/scmroot/xarchiver
Cloning into '/var/lib/mock/f40-build-804720-144599/root/chroot_tmpdir/scmroot/xarchiver'...
$ git fetch origin 18cbe117a83585e73575b0c70a27a2060fa9b6e9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/xarchiver
 * [new ref]         18cbe117a83585e73575b0c70a27a2060fa9b6e9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 18cbe11 Update to 0.5.4.23 (rhbz#2267148)