Force "internal" directive to display a custom 404?

[TECK]

Example:

error_page 404 /404.html;

location = /404.html {
    internal;
}

location /alpha {
    internal;
}

The proper behavior would be to display the custom 404.html in every
case, which does not.
I'm not sure this could be marked as new feature, or is feasible with
some configuration I don't know about it?

Thanks.

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,229365,229365#msg-229365