"error_page"& "return" bug?

[Nginx User]

Arrggghhh!


Server {
	error_page 503 /error_docs/custom503.html;
	if ( $request_uri !~ \.(jpg|gif|png|css|js)$ ) {
		set $tt  "T";
	}
	if ( $request_uri !~ ^/maintenance/$ ) {
    	set $tt  "${tt}T";
	}
	if ( $tt = TT ) {
		rewrite ^ /maintenance/ redirect;
	}
	location /maintenance {
		internal;
		return 503;
	}
	location /error_docs {
		internal;
		alias /server/path/to/error_docs/folder;
	}
}

Finally I promise :)