nginx regex map test

NGINX config:
=============

map $request_uri $new_uri {
    "~^/r(/[\S]+)\.(png|jpe?g)\?a=(\d+)$" $1.$2?x=$3;
}

server {
    listen       80;
    server_name  localhost;
    root   html;

    location / {
        index  index.html index.htm;
        if ($new_uri) {
            rewrite ^ $new_uri permanent;
        }
    }
}

cURL log:
=========

G:\OpenResty\OpenResty11782\x86>curl -v "http://localhost/r/some/path/image.jpg?a=100"
*   Trying 127.0.0.1...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 80 (#0)
> GET /r/some/path/image.jpg?a=100 HTTP/1.1
> Host: localhost
> User-Agent: curl/7.62.0
> Accept: */*
>
< HTTP/1.1 301 Moved Permanently
< Server: openresty/1.17.8.2
< Date: Tue, 20 Jul 2021 03:38:01 GMT
< Content-Type: text/html
< Content-Length: 175
< Location: http://localhost/some/path/image.jpg?x=100?a=100
< Connection: keep-alive
<
<html>
<head><title>301 Moved Permanently</title></head>
<body>
<center><h1>301 Moved Permanently</h1></center>
<hr><center>openresty/1.17.8.2</center>
</body>
</html>
* Connection #0 to host localhost left intact