This reverts commit 6d78fc4f90.
In some environments, this error is being seen:
2020-05-07 18:36:02.139422 | debian-buster | "msg": "stdout: The virtual environment was not created successfully because ensurepip is not\navailable. On Debian/Ubuntu systems, you need to install the python3-venv\npackage using the following command.\n\n apt-get install python3-venv\n\nYou may need to use sudo with that command. After installing the python3-venv\npackage, recreate your virtual environment.\n\nFailing command: ['/home/zuul/.local/tox/bin/python3', '-Im', 'ensurepip', '--upgrade', '--default-pip']\n\n"
Change-Id: I6d38bf16cc38020c53815dfa6ab94f8cab4de0a2