fix ipv6 configuration in ping6; complain more loudly on error
fix ipv6 configuration in ping6; complain more loudly on error

mor1/mirage-skeleton,Drup/mirage-skeleton,mirage/mirage-skeleton,djs55/mirage-skeleton,mor1/mirage-skeleton,Drup/mirage-skeleton,mirage/mirage-skeleton,djs55/mirage-skeleton