title: Duplicated log on single request with a minus sign at the end
body: <p>I have a setup where one nginx does reverse proxy to a second one.</p>
  
  <p>I observed in my logs, that one nginx sees two request but the second one sees just one of them. I also observed that the browser is just sending one request, so the duplication if exists, does not come from the client.</p>
  
  <p>Here is a sample of the logs:</p>
  
  <pre><code>nginx_1  | 192.168.64.8 - - [15/Jul/2016:11:43:32 +0000] "GET /images/mypic1.jpg HTTP/1.0" 200 9402 "http://localhost/es" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/50.0.2661.94 Safari/537.36"
  proxy_1  | 192.168.64.1 - - [15/Jul/2016:11:43:32 +0000] "GET /images/mypic1.jpg HTTP/1.1" 200 111773 "http://localhost/es" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/50.0.2661.94 Safari/537.36" "-"
  proxy_1  | 192.168.64.1 - - [15/Jul/2016:11:43:32 +0000] "GET /images/mypic1.jpg HTTP/1.1" 200 111773 "http://localhost/es" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/50.0.2661.94 Safari/537.36"
  proxy_1  | 192.168.64.1 - - [15/Jul/2016:11:43:32 +0000] "GET /images/mypic2.jpg HTTP/1.1" 200 25619 "http://localhost/es" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/50.0.2661.94 Safari/537.36" "-"
  proxy_1  | 192.168.64.1 - - [15/Jul/2016:11:43:32 +0000] "GET /images/mypic2.jpg HTTP/1.1" 200 25619 "http://localhost/es" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/50.0.2661.94 Safari/537.36"
  nginx_1  | 192.168.64.8 - - [15/Jul/2016:11:43:32 +0000] "GET /images/mypic2.jpg HTTP/1.0" 200 25619 "http://localhost/es" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/50.0.2661.94 Safari/537.36"
  </code></pre>
  
  <p>As you can see, proxy_1 is the nginx working as reverse proxy, and nginx_1 is the one receiving and processing the requests.</p>
  
  <p>In the end of every duplicated line you can see a "-" that I don't know what it means. I suspect is doing some sort of rewriting I'm not aware of but don't understand how it happens.</p>
  
  <p>Could you give me some clue about what is going on here?</p>
  
  <p>Here I also provide the server config:</p>
  
  <pre><code>access_log /dev/stdout;
  error_log /dev/stdout;
  
  server {
      listen 7000;
      listen 80;
  
      client_max_body_size 24M;
      server_name *.rareconnect.org;
  
      include /etc/nginx/params/gzip_on;
  
      location / {
          include /etc/nginx/params/proxy_pass_local_rareconnect_org_8000;
      }
  }
  </code></pre>
  
  <p>This is on top of the standard configuration of nginx:1.9.5 as appears in the official docker registry.</p>
  
  <pre><code>user  nginx;
  worker_processes  1;
  
  error_log  /var/log/nginx/error.log warn;
  pid        /var/run/nginx.pid;
  
  
  events {
      worker_connections  1024;
  }
  
  
  http {
      include       /etc/nginx/mime.types;
      default_type  application/octet-stream;
  
      log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                        '$status $body_bytes_sent "$http_referer" '
                        '"$http_user_agent" "$http_x_forwarded_for"';
  
      access_log  /var/log/nginx/access.log  main;
  
      sendfile        on;
      #tcp_nopush     on;
  
      keepalive_timeout  65;
  
      #gzip  on;
  
      include /etc/nginx/conf.d/*.conf;
  }
  </code></pre>
  
  <p>Thanks in advance.</p>