netlink_lib delete method doesn't work with python3

[Jakub Libosvar]

FAIL: neutron.tests.functional.agent.linux.test_netlink_lib.NetlinkLibTestCase.test_delete_tcp_entry
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/opt/stack/neutron/neutron/tests/base.py", line 140, in func
    return f(self, *args, **kwargs)
  File "/opt/stack/neutron/neutron/tests/functional/agent/linux/test_netlink_lib.py", line 106, in test_delete_tcp_entry
    self._delete_entry(tcp_entry, remain_entries, _zone)
  File "/opt/stack/neutron/neutron/tests/functional/agent/linux/test_netlink_lib.py", line 58, in _delete_entry
    self.assertEqual(remain_entries, entries_list)
  File "/opt/stack/neutron/.tox/dsvm-functional-python35/lib/python3.5/site-packages/testtools/testcase.py", line 411, in assertEqual
    self.assertThat(observed, matcher, message)
  File "/opt/stack/neutron/.tox/dsvm-functional-python35/lib/python3.5/site-packages/testtools/testcase.py", line 498, in assertThat
    raise mismatch_error
testtools.matchers._impl.MismatchError: !=:
reference = ((4, 'icmp', 8, 0, '1.1.1.1', '2.2.2.2', 3333, 51),
 (4, 'udp', 4, 5, '1.1.1.1', '2.2.2.2', 51))
actual = ((4, 'icmp', 8, 0, '1.1.1.1', '2.2.2.2', 3333, 51),
 (4, 'tcp', 1, 2, '1.1.1.1', '2.2.2.2', 51),
 (4, 'udp', 4, 5, '1.1.1.1', '2.2.2.2', 51))

2018-05-15 16:45:02.701 3976 WARNING neutron.privileged.agent.linux.netlink_lib [-] Netlink query failed