Navigation bar does not work with reverse proxy passing to subfolder

[johanehnberg]

A reverse proxy with a location statement such as this:

  location / {
    proxy_pass http://10.10.10.10:80/subdir/;
  }

And the responding server with the following responds with a location such as this:

location /subdir {
  root /var/www; #files reside under /var/www/subdir
  autoindex on;
  autoindex_format xml;
  xslt_stylesheet /srv/autoindex.xslt;
  dav_methods PUT DELETE MKCOL COPY MOVE;
  dav_ext_methods PROPFIND OPTIONS;
  create_full_put_path on;
  add_header X-Options 'WebDav';
}

Works otherwise perfectly, but the navigation bar adds /subdir/ on the path rather than being relative or browser-based.