As noted in the Ansible documentation, the 'ssh' portion of these variables is deprecated in Ansible 2.0:

Ansible 2.0 has deprecated the “ssh” from ansible_ssh_user, ansible_ssh_host, and
ansible_ssh_port to become ansible_user, ansible_host, and ansible_port. If you are using a
version of Ansible prior to 2.0, you should continue using the older style variables
(ansible_ssh_*). These shorter variables are ignored, without warning, in older versions of
Ansible.

The current version of Ansible in the Fedora repos is 2.4, so it is unlikely that users will run into problems with the shorter versions of these variables.