Problems with script name != "" and 'request.dispatch' config entry
I'm using a custom request dispatcher and enabling it with a 'request.dispatch' config entry inside the application config.
All works well until you try to mount that application at a different script name than the default.
If you use a script name like "/foo" you can reach your application at "/foo/" but not at "/foo" since trail in get_resource  is "" and there isn't any config entry at self.app.config for "" so CP defaults to the default dispatcher.
Note that to exercise this bug you need a dispatcher with a sufficiently different semantic that that used by CP otherwise the default dispatcher that kicks in may not raise a 404 error.