Simplify nginx.conf from initial, example configuration used in another, particular, test case:
  * temporarily remove SSL support as management of keys and certificates may yield security issues;
  * change pid file to /var/run/nginx.pid
  * change log directory to /var/log/nginx/
  * set the log format to the default combined mode (maybe temporarily, if the special format had reasons not understood yet)
  * set a default server name that returns error 404 (if no server name with rev. proxy matches)
  * comment out subs_filter instructions, probably unused for now
  * comment out adjunction of X-Real-IP and Accept-Encoding headers passed to the server by the reverse proxy