Aha !
That script provides correct output, thank you !
python ./nginx_python2
<<<nginx_status>>>
localhost 80 Active connections: 4
localhost 80 server accepts handled requests
localhost 80 18243 18243 254955
localhost 80 Reading: 0 Writing: 3 Waiting: 1
172.18.0.3 80 Active connections: 4
172.18.0.3 80 server accepts handled requests
172.18.0.3 80 18244 18244 254956
172.18.0.3 80 Reading: 0 Writing: 3 Waiting: 1
I guess it would be nice if the script from check_mk itself also would work 