$ git clone -n https://github.com/xcp-ng-rpms/xen.git /var/lib/mock/v8.3-u-stormi1-8827-27773/root/chroot_tmpdir/scmroot/xen
Cloning into '/var/lib/mock/v8.3-u-stormi1-8827-27773/root/chroot_tmpdir/scmroot/xen'...
$ git fetch origin 9f3868bd4c38b0dc927d3c86e5ea9c8c510aab41:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xen
 * [new ref]         9f3868bd4c38b0dc927d3c86e5ea9c8c510aab41 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9f3868b bump release for test build