send_header with NGX_HTTP_INTERNAL_SERVER_ERROR code

[itpp2012]

This is a general remark, adding stuff to handle a bad request, ea., will
eventually kill the performance, sending bad requests is a popular way to
create a DOS/DDOS attack since the server(the added module) has to process
them and do something while technically it makes no sense to do anything at
all.

All other normal requests have plenty of ways to handle overloading/doss-ing
without affecting other users, if you want to handle a bad request your
going to need to handle that as well, ergo leave bad requests to nginx.

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,267651,267653#msg-267653