$ git clone -n https://github.com/xcp-ng-rpms/xapi.git /var/lib/mock/v8.3-u-gtn2-8831-27775/root/chroot_tmpdir/scmroot/xapi
Cloning into '/var/lib/mock/v8.3-u-gtn2-8831-27775/root/chroot_tmpdir/scmroot/xapi'...
$ git fetch origin 17272f833f546f66f0e2432015b811233721be03:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xapi
 * [new ref]         17272f833f546f66f0e2432015b811233721be03 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 17272f8 bump release for test build