Could not load neutron_lbaas.drivers.haproxy.namespace_driver.HaproxyNSDriver

It seems the recent change[1] has broken the heat gate.

The neutron_lbaas.drivers.haproxy.namespace_driver.HaproxyNSDriver could not be loaded(used by heat) as you can see in the log[2]

Heat tests fail with the following error, as it can't reach the lb url.

-----------------------------------
2016-07-18 03:37:24.960600 | 2016-07-18 03:37:24.960 | Captured traceback:
2016-07-18 03:37:24.962940 | 2016-07-18 03:37:24.962 | ~~~~~~~~~~~~~~~~~~~
2016-07-18 03:37:24.964775 | 2016-07-18 03:37:24.964 | Traceback (most recent call last):
2016-07-18 03:37:24.966464 | 2016-07-18 03:37:24.966 | File "/opt/stack/new/heat/heat_integrationtests/scenario/test_autoscaling_lbv2.py", line 95, in test_autoscaling_loadbalancer_neutron
2016-07-18 03:37:24.967935 | 2016-07-18 03:37:24.967 | self.check_num_responses(lb_url, 1)
2016-07-18 03:37:24.971719 | 2016-07-18 03:37:24.970 | File "/opt/stack/new/heat/heat_integrationtests/scenario/test_autoscaling_lbv2.py", line 49, in check_num_responses
2016-07-18 03:37:24.973581 | 2016-07-18 03:37:24.973 | self.assertEqual(expected_num, len(resp))
2016-07-18 03:37:24.975288 | 2016-07-18 03:37:24.974 | File "/opt/stack/new/heat/.tox/integration/local/lib/python2.7/site-packages/testtools/testcase.py", line 411, in assertEqual
2016-07-18 03:37:24.977807 | 2016-07-18 03:37:24.977 | self.assertThat(observed, matcher, message)
2016-07-18 03:37:24.979352 | 2016-07-18 03:37:24.979 | File "/opt/stack/new/heat/.tox/integration/local/lib/python2.7/site-packages/testtools/testcase.py", line 498, in assertThat
2016-07-18 03:37:24.980967 | 2016-07-18 03:37:24.980 | raise mismatch_error
2016-07-18 03:37:24.983051 | 2016-07-18 03:37:24.982 | testtools.matchers._impl.MismatchError: 1 != 0
2016-07-18 03:37:24.984806 | 2016-07-18 03:37:24.984 |
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[1] https://github.com/openstack/neutron-lbaas/commit/56795d73094832b58b4804007ed31b5e896f59fc
[2] http://logs.openstack.org/56/343356/1/check/gate-heat-dsvm-functional-orig-mysql-lbaasv2/d1b8aca/logs/screen-q-lbaasv2.txt.gz#_2016-07-18_03_18_51_864