This demo not correct, the original childs1 can't pass the
the bdrv_is_root_node check in replcation_start().
Keep consistent with docs/COLO-FT.txt

Signed-off-by: Zhang Chen <chen.zhang@intel.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20211018085044.2788276-1-chen.zhang@intel.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>