proxy pass encoding % problem

[Krupa]

There are no rewrite policies.
location /gw_proxy {
            #internal;
            #resolver 8.8.8.8;
            proxy_http_version 1.1;
            proxy_pass  http://50.112.76.185:9001;
            proxy_pass_request_body off;
            proxy_set_header Content-Length 0;
        }

invoke nginx with this url :
http://54.245.39.250:8081/gw_proxy/test%2btest/
uri sent by nginx :  /gw_proxy/test%252btest/

local res = ngx.location.capture("/gw_proxy" .. ngx.var.request_uri, {
                  method = ngx_methods[gw_method],
                  body = "",
                  vars = {
                    }
                });

This is my configuration. Please advise.

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,238933,238935#msg-238935