Can't "unset" a remotes certs

Author: wibbit (wibbit)

Redmine Issue: 9061, https://pulp.plan.io/issues/9061

After erroneously creating a remote with a ca_cert, client_cert and client_key, I attempted to unset these values, however, it appeared to have no impact.

Below is a simple test to show the issue.

In [17]: remote_model = RpmRpmRemote(name="TestRemote", url='DuffURL', ca_cert="DuffCACert", client_cert="DuffClientCert", client_key="DuffClientKey")

In [18]: rpm_remote.create(rpm_rpm_remote=remote_model)
Out[18]:
{'ca_cert': 'DuffCACert',
'client_cert': 'DuffClientCert',
'connect_timeout': None,
'download_concurrency': None,
'headers': None,
'name': 'TestRemote',
'policy': 'immediate',
'proxy_url': None,
'pulp_created': datetime.datetime(2021, 7, 11, 20, 35, 52, 825025, tzinfo=tzutc()),
'pulp_href': '/pulp/api/v3/remotes/rpm/rpm/2ccbe163-75e5-4288-bd48-8ddca1e31fd8/',
'pulp_labels': {},
'pulp_last_updated': datetime.datetime(2021, 7, 11, 20, 35, 52, 825040, tzinfo=tzutc()),
'rate_limit': None,
'sles_auth_token': None,
'sock_connect_timeout': None,
'sock_read_timeout': None,
'tls_validation': True,
'total_timeout': None,
'url': 'DuffURL'}

In [19]: updated_remote_model = RpmRpmRemote(name="TestRemote", url='DuffURL', ca_cert=None, client_cert=None, client_key=None)

In [20]: rpm_remote.update(rpm_rpm_remote_href='/pulp/api/v3/remotes/rpm/rpm/2ccbe163-75e5-4288-bd48-8ddca1e31fd8/', rpm_rpm_remote=updated_remote_model)
Out[20]: {'task': '/pulp/api/v3/tasks/f1e654a4-4f64-4a18-8311-60827b8be13a/'}

In [21]: rpm_remote.read(rpm_rpm_remote_href='/pulp/api/v3/remotes/rpm/rpm/2ccbe163-75e5-4288-bd48-8ddca1e31fd8/')
Out[21]:
{'ca_cert': 'DuffCACert',
'client_cert': 'DuffClientCert',
'connect_timeout': None,
'download_concurrency': None,
'headers': None,
'name': 'TestRemote',
'policy': 'immediate',
'proxy_url': None,
'pulp_created': datetime.datetime(2021, 7, 11, 20, 35, 52, 825025, tzinfo=tzutc()),
'pulp_href': '/pulp/api/v3/remotes/rpm/rpm/2ccbe163-75e5-4288-bd48-8ddca1e31fd8/',
'pulp_labels': {},
'pulp_last_updated': datetime.datetime(2021, 7, 11, 20, 37, 1, 169677, tzinfo=tzutc()),
'rate_limit': None,
'sles_auth_token': None,
'sock_connect_timeout': None,
'sock_read_timeout': None,
'tls_validation': True,
'total_timeout': None,
'url': 'DuffURL'}

In [23]: rpm_remote.update(rpm_rpm_remote_href='/pulp/api/v3/remotes/rpm/rpm/2ccbe163-75e5-4288-bd48-8ddca1e31fd8/', rpm_rpm_remote=updated_remote_model2)
Out[23]: {'task': '/pulp/api/v3/tasks/956a90d6-91e5-4820-a6bf-2b7aed4bb0a8/'}

In [24]: rpm_remote.read(rpm_rpm_remote_href='/pulp/api/v3/remotes/rpm/rpm/2ccbe163-75e5-4288-bd48-8ddca1e31fd8/')
Out[24]:
{'ca_cert': 'DuffCACert2',
'client_cert': 'DuffClientCert2',
'connect_timeout': None,
'download_concurrency': None,
'headers': None,
'name': 'TestRemote',
'policy': 'immediate',
'proxy_url': None,
'pulp_created': datetime.datetime(2021, 7, 11, 20, 35, 52, 825025, tzinfo=tzutc()),
'pulp_href': '/pulp/api/v3/remotes/rpm/rpm/2ccbe163-75e5-4288-bd48-8ddca1e31fd8/',
'pulp_labels': {},
'pulp_last_updated': datetime.datetime(2021, 7, 11, 20, 43, 1, 910725, tzinfo=tzutc()),
'rate_limit': None,
'sles_auth_token': None,
'sock_connect_timeout': None,
'sock_read_timeout': None,
'tls_validation': True,
'total_timeout': None,
'url': 'DuffURL'}

Start with the rpm_remote.update and rpm_remote.read calls shown in the report, then trace how the remote update handles ca_cert, client_cert, and client_key values of None. Reproduce the create, update, and read sequence and consider the issue done when reading the remote shows those certificate fields unset after the update.