The `k8_common.py` module is not currently available in an official release of Ansible. It is part of Ansible, and you'll find it on the `devel` branch, so at some point it will make it into a release. Until then, it's included here in order for convenience.

If you have uncovered a problem with it, or would like to make a change, please open issue and submit pull requess at the [Ansible repo](https://github.com/ansible/ansible).