[stable/liberty] LBaaS v2 haproxy: lbaas namespaces are not deleted after cleanup

After below steps, I see config got cleaned and left q-lbaas namespace on the controller.

Steps:
Create LBaaS loadbalancer for subnet
Create listener
Create pool and add instances as members
Delete pool
Delete listener
Delete LB

stack@controller:/opt/stack/logs$ sudo ip netns exec qlbaas-e61a1fbf-a897-41e4-bf05-459c0c2459a2 ifconfig
lo Link encap:Local Loopback
          inet addr:127.0.0.1 Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING MTU:65536 Metric:1
          RX packets:26 errors:0 dropped:0 overruns:0 frame:0
          TX packets:26 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:2368 (2.3 KB) TX bytes:2368 (2.3 KB)

stack@controller:/opt/stack/logs$
2016-06-30 05:03:04.831 DEBUG oslo_concurrency.lockutils [req-cfeb0e31-759d-468c-9542-9bf7cb3e690d admin ce1d087209c64df4b7e8007dc35def22] Lock "haproxy-driver" acquired by "neutron_lbaas.drivers.haproxy.namespace_driver.deploy_instance" :: waited 0.000s from (pid=8672) inner /usr/local/lib/python2.7/dist-packages/oslo_concurrency/lockutils.py:253
2016-06-30 05:03:04.831 DEBUG neutron.agent.linux.utils [req-cfeb0e31-759d-468c-9542-9bf7cb3e690d admin ce1d087209c64df4b7e8007dc35def22] Running command (rootwrap daemon): ['ip', '-o', 'netns', 'list'] from (pid=8672) execute_rootwrap_daemon /opt/stack/neutron/neutron/agent/linux/utils.py:101
2016-06-30 05:03:04.835 DEBUG neutron.agent.linux.utils [req-cfeb0e31-759d-468c-9542-9bf7cb3e690d admin ce1d087209c64df4b7e8007dc35def22]
Command: ['ip', '-o', 'netns', 'list']
Exit code: 0
 from (pid=8672) execute /opt/stack/neutron/neutron/agent/linux/utils.py:156
2016-06-30 05:03:04.837 DEBUG neutron.agent.linux.utils [req-cfeb0e31-759d-468c-9542-9bf7cb3e690d admin ce1d087209c64df4b7e8007dc35def22] Running command (rootwrap daemon): ['ip', 'netns', 'exec', 'qlbaas-e61a1fbf-a897-41e4-bf05-459c0c2459a2', 'haproxy', '-f', '/opt/stack/data/neutron/lbaas/v2/e61a1fbf-a897-41e4-bf05-459c0c2459a2/haproxy.conf', '-p', '/opt/stack/data/neutron/lbaas/v2/e61a1fbf-a897-41e4-bf05-459c0c2459a2/haproxy.pid', '-sf', '3794'] from (pid=8672) execute_rootwrap_daemon /opt/stack/neutron/neutron/agent/linux/utils.py:101
2016-06-30 05:03:04.867 DEBUG neutron.agent.linux.utils [req-cfeb0e31-759d-468c-9542-9bf7cb3e690d admin ce1d087209c64df4b7e8007dc35def22]
Command: ['ip', 'netns', 'exec', u'qlbaas-e61a1fbf-a897-41e4-bf05-459c0c2459a2', 'haproxy', '-f', u'/opt/stack/data/neutron/lbaas/v2/e61a1fbf-a897-41e4-bf05-459c0c2459a2/haproxy.conf', '-p', u'/opt/stack/data/neutron/lbaas/v2/e61a1fbf-a897-41e4-bf05-459c0c2459a2/haproxy.pid', '-sf', '3794']
Exit code: 0