Tempest test PortsIpV6TestJSON.test_update_port_with_security_group_and_extra_attributes failed due to fixed_ips field not updated

R3.0.2.0 Build 52 Liberty

Tempest test tempest.api.network.test_ports.PortsIpV6TestJSON.test_update_port_with_security_group_and_extra_attributes fails with below exception :
----------
The port update is updating subnet_id in the fixed_ips field and asserts if it has not happened

Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/tempest/api/network/test_ports.py", line 314, in test_update_port_with_security_group_and_extra_attributes
    [data_utils.rand_name('secgroup')])
  File "/usr/local/lib/python2.7/dist-packages/tempest/api/network/test_ports.py", line 305, in _update_port_with_security_groups
    port_show['fixed_ips'][0]['subnet_id'])
  File "/usr/lib/python2.7/dist-packages/testtools/testcase.py", line 348, in assertEqual
    self.assertThat(observed, matcher, message)
  File "/usr/lib/python2.7/dist-packages/testtools/testcase.py", line 433, in assertThat
    raise mismatch_error
MismatchError: !=:
reference = u'04777df1-2f2e-457f-be9f-bda33b47b13f'
actual = u'501adb1d-6db8-4d86-8e37-0852439a8d1e'

-----------

root@nodeb5:/var/log/neutron# neutron port-show 3b3d5169-6b39-4f72-b286-65e1fbdd1c32
+---------------------+--------------------------------------------------------------------------------+
| Field | Value |
+---------------------+--------------------------------------------------------------------------------+
| admin_state_up | False |
| binding:vif_details | {"port_filter": true} |
| binding:vif_type | vrouter |
| binding:vnic_type | normal |
| device_id | |
| device_owner | |
| fixed_ips | {"subnet_id": "501adb1d-6db8-4d86-8e37-0852439a8d1e", "ip_address": "2003::3"} |
| id | 3b3d5169-6b39-4f72-b286-65e1fbdd1c32 |
| mac_address | 02:3b:3d:51:69:6b |
| name | tempest-port--444854566 |
| network_id | c578cf3f-ca36-4aeb-ac40-c877efc54d1d |
| security_groups | ce3ca78c-e915-41fa-a6f6-ca748243ea26 |
| status | DOWN |
| tenant_id | 464d4e927fa04f30bfc7e301701fba56 |
+---------------------+--------------------------------------------------------------------------------+
root@nodeb5:/var/log/neutron# neutron subnet-list | grep 04777df1
| 04777df1-2f2e-457f-be9f-bda33b47b13f | | 2003:0:0:1::/64 | {"start": "2003:0:0:1::2", "end": "2003::1:ffff:ffff:ffff:fffe"} |
root@nodeb5:/var/log/neutron#

Test code :

        subnet_1 = self.create_subnet(self.network)
        self.addCleanup(self.subnets_client.delete_subnet, subnet_1['id'])
        fixed_ip_1 = [{'subnet_id': subnet_1['id']}]

        security_groups_list = list()
        sec_grps_client = self.security_groups_client
        for name in security_groups_names:
            group_create_body = sec_grps_client.create_security_group(
                name=name)
            self.addCleanup(self.security_groups_client.delete_security_group,
                            group_create_body['security_group']['id'])
            security_groups_list.append(group_create_body['security_group']
                                        ['id'])
        # Create a port
        sec_grp_name = data_utils.rand_name('secgroup')
        security_group = sec_grps_client.create_security_group(
            name=sec_grp_name)
        self.addCleanup(self.security_groups_client.delete_security_group,
                        security_group['security_group']['id'])
        post_body = {
            "name": data_utils.rand_name('port-'),
            "security_groups": [security_group['security_group']['id']],
            "network_id": self.network['id'],
            "admin_state_up": True,
            "fixed_ips": fixed_ip_1}
        body = self.ports_client.create_port(**post_body)
        self.addCleanup(self.ports_client.delete_port, body['port']['id'])
        port = body['port']

        # Update the port with security groups
        subnet_2 = self.create_subnet(self.network)
        fixed_ip_2 = [{'subnet_id': subnet_2['id']}]
        update_body = {"name": data_utils.rand_name('port-'),
                       "admin_state_up": False,
                       "fixed_ips": fixed_ip_2,
                       "security_groups": security_groups_list}
        body = self.ports_client.update_port(port['id'], **update_body)
        port_show = body['port']
        # Verify the security groups and other attributes updated to port
        exclude_keys = set(port_show).symmetric_difference(update_body)
        exclude_keys.add('fixed_ips')
        exclude_keys.add('security_groups')
        self.assertThat(port_show, custom_matchers.MatchesDictExceptForKeys(
                        update_body, exclude_keys))
        self.assertEqual(fixed_ip_2[0]['subnet_id'],
                         port_show['fixed_ips'][0]['subnet_id']) <<<<<<< Fails here

        for security_group in security_groups_list:
            self.assertIn(security_group, port_show['security_groups'])