Redmine

I've just upgraded from 1.3 to 2.0.3 and am getting 404'ed on my sub-URI root. production.log shows:
ActionController::RoutingError (No route matches [GET] "/redmine")

The relative URI was set in my lighttpd configuration by setting the RAILS_RELATIVE_URL_ROOT environment variable, though some searching has suggested that this no longer works in more recent versions of Rails. It wasn't working either way, and I commented it out.

http://www.redmine.org/projects/redmine/wiki/HowTo_Install_Redmine_in_a_sub-URI suggests the following:
Redmine::Utils::relative_url_root = "/redmine"

However, this doesn't seem to change anything and I still get the same error. The wiki page hasn't been updated in a while. Is there a new way to set the relative root, or should I be looking at something else?