$upstream_addr returning "-" only on requests with "del" in them

[ywarnier]

And the usual debug information I just found on
https://www.nginx.com/resources/wiki/start/topics/tutorials/debugging/ that
I should provide (very sorry for doing that in 3 parts, won't happen
again):

#### nginx -V
nginx version: nginx/1.10.0 (Ubuntu)
built with OpenSSL 1.0.2g  1 Mar 2016
TLS SNI support enabled
configure arguments: --with-cc-opt='-g -O2 -fPIE -fstack-protector-strong
-Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2'
--with-ld-opt='-Wl,-Bsymbolic-functions -fPIE -pie -Wl,-z,relro -Wl,-z,now'
--prefix=/usr/share/nginx --conf-path=/etc/nginx/nginx.conf
--http-log-path=/var/log/nginx/access.log
--error-log-path=/var/log/nginx/error.log --lock-path=/var/lock/nginx.lock
--pid-path=/run/nginx.pid --http-client-body-temp-path=/var/lib/nginx/body
--http-fastcgi-temp-path=/var/lib/nginx/fastcgi
--http-proxy-temp-path=/var/lib/nginx/proxy
--http-scgi-temp-path=/var/lib/nginx/scgi
--http-uwsgi-temp-path=/var/lib/nginx/uwsgi --with-debug --with-pcre-jit
--with-ipv6 --with-http_ssl_module --with-http_stub_status_module
--with-http_realip_module --with-http_auth_request_module
--with-http_addition_module --with-http_dav_module --with-http_geoip_module
--with-http_gunzip_module --with-http_gzip_static_module
--with-http_image_filter_module --with-http_v2_module --with-http_sub_module
--with-http_xslt_module --with-stream --with-stream_ssl_module --with-mail
--with-mail_ssl_module --with-threads
--add-module=/build/nginx-pzhfc2/nginx-1.10.0/debian/modules/nginx-auth-pam
--add-module=/build/nginx-pzhfc2/nginx-1.10.0/debian/modules/nginx-dav-ext-module
--add-module=/build/nginx-pzhfc2/nginx-1.10.0/debian/modules/nginx-echo
--add-module=/build/nginx-pzhfc2/nginx-1.10.0/debian/modules/nginx-upstream-fair
--add-module=/build/nginx-pzhfc2/nginx-1.10.0/debian/modules/ngx_http_substitutions_filter_module

#### cat /etc/nginx/nginx.conf

user www-data;
worker_processes auto;
pid /run/nginx.pid;

events {
        worker_connections 768;
}

http {
        sendfile on;
        tcp_nopush on
        tcp_nodelay on;
        keepalive_timeout 65;
        types_hash_max_size 2048;
        client_max_body_size 50m;
        # Avoid timeouts
        send_timeout         600;
        proxy_send_timeout   600;
        proxy_read_timeout   600;

        include /etc/nginx/mime.types;
        default_type application/octet-stream;

        access_log /var/log/nginx/access.log;
        error_log /var/log/nginx/error.log;
        log_format compression '$remote_addr - $remote_user [$time_local] '
                           '"$request" $status $body_bytes_sent '
                           '"$http_referer" "$http_user_agent"
"$gzip_ratio"'
                           '[$upstream_addr: $request
|$upstream_connect_time|$upstream_header_time|$upstream_response_time|$request_time|$bytes_sent|$pipe|$upstream_status]';

        gzip on;
        gzip_disable "msie6";
        include /etc/nginx/conf.d/*.conf;
        include /etc/nginx/sites-enabled/*;
}


#### cat sites-enabled/load-balancer 

upstream apache {
  server webdevw1.myorg.edu;
}

#### cat sites-enabled/dev.www.myorg.edu

server {
  listen 80;
  listen [::]:80;
  server_name dev.www.myorg.edu;
  error_log /var/log/nginx/www.myorg.edu-error.log debug;
  access_log /var/log/nginx/www.myorg.edu-access.log compression;
  location / {
    proxy_buffers 64 128k;
    proxy_buffer_size 2k;
    proxy_http_version 1.1;
    proxy_set_header Connection "";
    proxy_set_header Host $host;
    proxy_set_header X-Forwarded-For $remote_addr;
    proxy_pass http://apache;
  }
}

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,273895,273898#msg-273898