Steps to reproduce:

 * Running ikiwiki version 3.20130904.1ubuntu1 on Ubuntu 14.04 LTS
 * ikiwiki accessed via `https://DOMAIN/wiki/ikiwiki.cgi` using fcgiwrap and Nginx
 * Start ikiwiki site
 * Edit an existing page

What should happen:

 * Change is immediately available

What happens instead:

 * Change is sometimes not immediately available
 * After (approx) 1-2 minutes, change is available

Other notes:

 * Similarly for creating new pages
 * Not consistent (the next edit may be visible immediately)
 * If changes are visible from one browser, may not be visible from another browser on a different machine, logged in as the same user (admin)
 * Seems to be happening less / not at all after running the site for approx 30-60 minutes
 * fcgiwrap is invoked with Supervisor (aka supervisord)
 * Related Nginx location blocks:

```
# non-wiki files at DOMAIN/...
location / {
    try_files $uri $uri/ /index.html =404;
}

# wiki files at DOMAIN/wiki
location /wiki {
    alias /home/USERNAME/public_html/WIKINAME;
}

# wiki script at DOMAIN/wiki/ikiwiki.cgi
location /wiki/ikiwiki.cgi {
    fastcgi_pass  unix:/tmp/fcgi.socket;
    fastcgi_index ikiwiki.cgi;
    fastcgi_param SCRIPT_FILENAME    /home/USERNAME/public_html/WIKINAME/ikiwiki.cgi;
    fastcgi_param DOCUMENT_ROOT    /home/USERNAME/public_html/WIKINAME;
    include /etc/nginx/fastcgi_params;
}
```

Please let me know if this is expected/known, and/or if there's anything helpful I can add to the report.
