SYMC: "__no_rule__" security group read fails even with multitenancy set to False

[Varun Lodaya]

When all the security groups are deleted from a port, "__no_default__" security group gets added to the port which has "user_visible" flag set to False. Hence, the security group is not readable. Ideally, with multi-tenancy set to False, objects with user_visible as False should still be readable, but it's not.
Also, since this security group is not added by user but by the system, while reading/updating the relevant port, it should not throw a 500
Following is the backtrace we see:

The above is a description of an error in a Python program. Here is
the original traceback:

Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/vnc_openstack/neutron_plugin_interface.py", line 409, in plugin_update_port
    port['resource'])
  File "/usr/lib/python2.7/dist-packages/vnc_openstack/neutron_plugin_db.py", line 2220, in wrapper
    return func(self, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/vnc_openstack/neutron_plugin_db.py", line 3636, in port_update
    port_obj = self._port_neutron_to_vnc(port_q, None, UPDATE)
  File "/usr/lib/python2.7/dist-packages/vnc_openstack/neutron_plugin_db.py", line 1780, in _port_neutron_to_vnc
    sg_obj = self._vnc_lib.security_group_read(id=sg_id)
  File "/usr/lib/python2.7/dist-packages/vnc_api/gen/vnc_api_client_gen.py", line 4071, in security_group_read
    content = self._request_server(rest.OP_GET, uri, query_params)
  File "/usr/lib/python2.7/dist-packages/vnc_api/vnc_api.py", line 497, in _request_server
    retry_count=retry_count)
  File "/usr/lib/python2.7/dist-packages/vnc_api/vnc_api.py", line 538, in _request
    % (op, url, data, content))
NoIdError: Unknown id: Error: oper 2 url /security-group/02971ec5-becf-4d45-a0f3-b9fc9efcb464 body {'exclude_back_refs': True, 'exclude_children': True} response This object is not visible by users: 02971ec5-becf-4d45-a0f3-b9fc9efcb464

[Sachin Bansal (sbansal)]

In 2.20 or earlier, port-show would have listed NO_RULE SG as the security group attached. We changed that in master so that it is completely hidden from neutron/nova, so this problem should not arise.