the nginx cookbook supports two methods to use the official nginx repo instead of the one delivered with the operating system.

It is possible via

"nginx" : { "repo_source" : "nginx" }

and

"nginx" : { "install_method" : "repo" }

Currently we only detect the second approach, but not the first one. See
https://github.com/TelekomLabs/chef-nginx-hardening/blob/master/recipes/default.rb#L29