$ git clone -n https://github.com/xcp-ng-rpms/samba.git /var/lib/mock/v8.3-u-pcoval2-10436-28997/root/chroot_tmpdir/scmroot/samba
Cloning into '/var/lib/mock/v8.3-u-pcoval2-10436-28997/root/chroot_tmpdir/scmroot/samba'...
$ git fetch origin 4aa5292d30f16d4669f1ecd7a792ce6ddfd282d3:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/samba
 * [new ref]         4aa5292d30f16d4669f1ecd7a792ce6ddfd282d3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4aa5292 bump release for test build