The --base option (defaulting to "/") essentially configures the
base_url in http.c which was introduced previously. Now darkstat works
without too much magic behind a reverse proxy.
My mod_proxy config changed from
ProxyPass /darkstat http://localhost:666
<Location /darkstat/>
ProxyPassReverse /
SetOutputFilter proxy-html
ProxyHTMLURLMap / /darkstat/
RequestHeader unset Accept-Encoding
</Location>
Redirect permanent /graphs.xml /darkstat/graphs.xml
to the simpler
ProxyPass /darkstat/ http://localhost:666/darkstat/
ProxyPassReverse /darkstat/ http://localhost:666/darkstat/
(the ProxyPassReverse isn't even needed since darkstat doesn't generate
any Location headers).