These warnings are described as:

 W0612: Used when a variable is defined but not used.
 W0622: Used when a variable or function override a built-in.

After a suggestion from Andrei Stepanov, we decided to immediately
enable these.

Rerefence: https://pagure.io/standard-test-roles/pull-request/144
Reference: https://trello.com/c/Ohh7Q6qj/1183-enable-w-in-travis-make-checkSigned-off-by: NCleber Rosa <crosa@redhat.com>