Non-working example of clobbering credit card numbers in nginx.conf

nginx.conf

http {
    include       mime.types;                                                                                                                                                                                      

    log_format  main  '$remote_addr - $remote_user [$time_local] "$request_munged" '
        '$status $body_bytes_sent $request_time/$upstream_response_time '
        '"$http_referer" "$http_user_agent"';                                                                                                                                                                      

    [...]

    server {
        location / {
            # The original request
            set $request_munged $request;                                                                                                                                                                     

            # Strip some secret data out before logging it
            if ($request_munged ~ /^(.*?&credit_card_number=)[^&]+(.*?)$/) {
                set $request_munged "$1SEEKRT$2";                                                                                                                                                                  
            }
            uwsgi_pass unix:/var/run/uwsgi/uwsgi.sock;                                                                                                                                                             
        }
    }
}