Container Support

From pulplift using the latest ansible-pulp:
```
TASK [pulp : Install Pulp plugins from source] ***************************
ok: [pulp3-source-fedora31] => (item={'key': 'pulp-certguard', 'value': {'source_dir': '/home/vagrant/devel/pulp-certguard'}})
failed: [pulp3-source-fedora31] (item={'key': 'pulp-container', 'value': {'source_dir': '/home/vagrant/devel/pulp_container'}}) => {
"ansible_loop_var": "item",
"changed": false,
"cmd": [
"/usr/local/lib/pulp/bin/pip3",
"install",
"-e",
"/home/vagrant/devel/pulp_container"
],
"item": {
"key": "pulp-container",
"value": {
"source_dir": "/home/vagrant/devel/pulp_container"
}
}
}

MSG:

stdout: Obtaining file:///home/vagrant/devel/pulp_container
Installing build dependencies: started
Installing build dependencies: finished with status 'done'
Getting requirements to build wheel: started
Getting requirements to build wheel: finished with status 'done'
Preparing wheel metadata: started
Preparing wheel metadata: finished with status 'error'

:stderr: ERROR: Complete output from command /usr/local/lib/pulp/bin/python3 /usr/local/lib/pulp/lib64/python3.7/site-packages/pip/_vendor/pep517/_in_process.py prepare_metadata_for_build_wheel /tmp/tmpxzg6tty3:
ERROR: Warning: 'classifiers' should be a list, got type 'tuple'
running dist_info
creating /home/vagrant/devel/pulp_container/pip-wheel-metadata/pulp_container.egg-info
writing /home/vagrant/devel/pulp_container/pip-wheel-metadata/pulp_container.egg-info/PKG-INFO
writing dependency_links to /home/vagrant/devel/pulp_container/pip-wheel-metadata/pulp_container.egg-info/dependency_links.txt
writing entry points to /home/vagrant/devel/pulp_container/pip-wheel-metadata/pulp_container.egg-info/entry_points.txt
writing requirements to /home/vagrant/devel/pulp_container/pip-wheel-metadata/pulp_container.egg-info/requires.txt
writing top-level names to /home/vagrant/devel/pulp_container/pip-wheel-metadata/pulp_container.egg-info/top_level.txt
writing manifest file '/home/vagrant/devel/pulp_container/pip-wheel-metadata/pulp_container.egg-info/SOURCES.txt'
reading manifest file '/home/vagrant/devel/pulp_container/pip-wheel-metadata/pulp_container.egg-info/SOURCES.txt'
writing manifest file '/home/vagrant/devel/pulp_container/pip-wheel-metadata/pulp_container.egg-info/SOURCES.txt'
creating '/home/vagrant/devel/pulp_container/pip-wheel-metadata/pulp_container.dist-info'
adding license file "LICENSE" (matched pattern "LICEN[CS]E*")
adding license file "AUTHORS" (matched pattern "AUTHORS*")
/usr/lib/python3.7/site-packages/setuptools/dist.py:474: UserWarning: Normalizing '1.1.0.dev' to '1.1.0.dev0'
normalized_version,
Traceback (most recent call last):
File "/usr/local/lib/pulp/lib64/python3.7/site-packages/pip/_vendor/pep517/_in_process.py", line 207, in <module>
main()
File "/usr/local/lib/pulp/lib64/python3.7/site-packages/pip/_vendor/pep517/_in_process.py", line 197, in main
json_out['return_val'] = hook(**hook_input['kwargs'])
File "/usr/local/lib/pulp/lib64/python3.7/site-packages/pip/_vendor/pep517/_in_process.py", line 69, in prepare_metadata_for_build_wheel
return hook(metadata_directory, config_settings)
File "/usr/lib/python3.7/site-packages/setuptools/build_meta.py", line 170, in prepare_metadata_for_build_wheel
assert len(dist_infos) == 1
AssertionError
----------------------------------------
ERROR: Command "/usr/local/lib/pulp/bin/python3 /usr/local/lib/pulp/lib64/python3.7/site-packages/pip/_vendor/pep517/_in_process.py prepare_metadata_for_build_wheel /tmp/tmpxzg6tty3" failed with error code 1 in /home/vagrant/devel/pulp_container
WARNING: You are using pip version 19.1.1, however version 19.3.1 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.

ok: [pulp3-source-fedora31] => (item={'key': 'pulp-rpm', 'value': {'source_dir': '/home/vagrant/devel/pulp_rpm', 'prereq_role': 'pulp.pulp_rpm_prerequisites'}})
ok: [pulp3-source-fedora31] => (item={'key': 'pulp-file', 'value': {'source_dir': '/home/vagrant/devel/pulp_file'}})

PLAY RECAP ***************************************************************
pulp3-source-fedora31 : ok=20 changed=10 unreachable=0 failed=1 skipped=12 rescued=0 ignored=0

Ansible failed to complete successfully. Any error output should be
visible above. Please fix these errors and try again.
```

I was able to workaround it by running:
```
$ vagrant ssh pulp3-source-fedora31
$ source /usr/local/lib/pulp/activate
$ pip instal --upgrade pip
```

These are the vars I'm using (pulp_use_system_wide_pkgs = true might be the issue).
```
[mdepaulo@mdepaulo pulplift]$ cat local.dev-config.yml

1. Options
   pulp_devel_supplement_bashrc: true
   pulp_default_admin_password: password
   pulp_install_plugins:
   # pulp-ansible:
   # source_dir: "/home/vagrant/devel/pulp_ansible"
   pulp-certguard:
   source_dir: "/home/{{ ansible_user }}/devel/pulp-certguard"
   # pulp-cookbook:
   # source_dir: "/home/vagrant/devel/pulp_cookbook"
   # pulp-deb:
   # source_dir: "/home/vagrant/devel/pulp_deb"
   pulp-container:
   source_dir: "/home/{{ ansible_user }}/devel/pulp_container"
   # pulp-gem:
   # source_dir: "/home/vagrant/devel/pulp_gem"
   # pulp-maven:
   # source_dir: "/home/vagrant/devel/pulp_maven"
   # pulp-python:
   # source_dir: "/home/vagrant/devel/pulp_python"
   pulp-rpm:
   source_dir: "/home/{{ ansible_user }}/devel/pulp_rpm"
   prereq_role: "pulp.pulp_rpm_prerequisites"
   pulp-file:
   source_dir: "/home/{{ ansible_user }}/devel/pulp_file"

1. Vagrant source install Required
   pulp_user: "{{ ansible_user }}"
   developer_user: "{{ ansible_user }}"
   developer_user_home: "/home/{{ ansible_user }}"
   pulp_source_dir: "{{ developer_user_home }}/devel/pulpcore"
2. Uncomment if using pulp-rpm
   pulp_use_system_wide_pkgs: true
   pulp_settings:
   secret_key: "unsafe_default"
   content_origin: "http://{{ ansible_fqdn }}"
   ```