$ git clone -n https://github.com/xcp-ng-rpms/gnutls.git /var/lib/mock/v8.3-u-pcoval2-10432-28994/root/chroot_tmpdir/scmroot/gnutls
Cloning into '/var/lib/mock/v8.3-u-pcoval2-10432-28994/root/chroot_tmpdir/scmroot/gnutls'...
$ git fetch origin 5bd28e50f9ec1cb099e76ba32ed6dc98fe931bf6:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/gnutls
 * [new ref]         5bd28e50f9ec1cb099e76ba32ed6dc98fe931bf6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5bd28e5 bump release for test build