$ git clone -n https://src.fedoraproject.org/rpms/xxhash.git /var/lib/mock/f42-build-867559-175628/root/chroot_tmpdir/scmroot/xxhash
Cloning into '/var/lib/mock/f42-build-867559-175628/root/chroot_tmpdir/scmroot/xxhash'...
$ git fetch origin 013c0840baa0194ecd4f6d48576c094ee42d493b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/xxhash
 * [new ref]         013c0840baa0194ecd4f6d48576c094ee42d493b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 013c084 Update to version 0.8.3