The k8_common.py and openshift_common.py modules are not currently available in an official release of Ansible. They are part of Ansible, as you'll find them in the devel branch. At some point they will make it into an official release. Until then, they're included here for convenience.
If you have uncovered a problem, or would like to make a change, please open an issue and submit pull requess at the Ansible repo.