I am trying to configure cacti under nginx. It makes heavy use of the $_SERVER['PHP_SELF'] variable, but this isn't getting set. I've tried setting it explicitly; e.g.

fastcgi_param PHP_SELF $fastcgi_script_name;

but when I dump the $_SERVER variable from PHP it's still not set. I've tried passing other variables to PHP this way as a test, and I can see them when I dump $_SERVER, so I'm wondering if nginx is stripping this, and if there's a workaround. I'm using the Ubuntu nginx 0.6.35 package under jaunty.