looking at travis, it seems something is still trying to write to /var/log/nginx - https://travis-ci.org/FriendsOfSymfony/FOSHttpCache/jobs/20242224

if you find a way to never have nginx write there, would be cool. but as it is just a test setup, i don't think it would be a big issue if we `sudo chmod -R 777 /var/log/nginx` in the travis setup script and let nginx just write to its default logfiles.