Comment 21 for bug 1624791

I can confirm this fixes this the issue.
https://bugs.launchpad.net/openstack-ansible/+bug/1624791/comments/17

Upgrading cryptography within the venv also seems to work, but that's probably not feasible because of stable/newton's upper constraint requirements.
https://github.com/openstack/requirements/blob/stable/newton/upper-constraints.txt#L95