Why can't I use a dynamic error_log location like I do with access_log? Example config:

server_name ~^(?<username>.+)\.my-domain\.com$;

root /srv/www/accounts/$username/app;

access_log /var/log/nginx/accounts/$username/access.log;
error_log /var/log/nginx/accounts/$username/error.log;

This does not work, since for some reason nginx chokes out on the dynamic error_log location. Feature request?