rhel-osp-director: Upgrade of undercloud 7.2  to 8.0 fails with: "Unable to complete operation on subnet <ID>. One or more ports have an IP allocation from this subnet.


Environment:
openstack-tripleo-heat-templates-0.8.7-2.el7ost.noarch
openstack-tripleo-0.0.7-1.el7ost.noarch
instack-undercloud-2.2.1-2.el7ost.noarch
openstack-tripleo-common-0.0.2-5.el7ost.noarch
openstack-tripleo-image-elements-0.9.7-2.el7ost.noarch
openstack-tripleo-puppet-elements-0.0.2-1.el7ost.noarch


Steps to reproduce:
1. Deploy 7.2 undercloud and HA overcloud with vxlan network backend + network isolation.
2. Attempt to upgrade the undercloud to 8.0: 
   a. Update the repos and RPMs.
   b. Run "openstack undercloud install"

Result:
+ echo 'New cidr 192.168.0.0/24 does not equal old cidr 10.19.94.0/24'
New cidr 192.168.0.0/24 does not equal old cidr 10.19.94.0/24
+ echo 'Will attempt to delete and recreate subnet 23e12754-0acd-4048-8981-59dfa94742cf
dc35b294-069a-4206-8e20-03464f9dd632
c8766472-5027-4466-b96a-e96d65f636c8
ad30e2c9-8ce8-43bf-9c00-8441328237be
43ec90c8-cdeb-4c5a-b71b-25ab1a03c6db
f273ff74-6042-4834-8a9b-8071d43f751d'
Will attempt to delete and recreate subnet 23e12754-0acd-4048-8981-59dfa94742cf
dc35b294-069a-4206-8e20-03464f9dd632
c8766472-5027-4466-b96a-e96d65f636c8
ad30e2c9-8ce8-43bf-9c00-8441328237be
43ec90c8-cdeb-4c5a-b71b-25ab1a03c6db
f273ff74-6042-4834-8a9b-8071d43f751d
+ '[' 1 -eq 1 ']'
+ grep start
+ neutron subnet-list
| ad30e2c9-8ce8-43bf-9c00-8441328237be | storage_subnet      | 10.19.95.0/24    | {"start": "10.19.95.10", "end": "10.19.95.200"}       |
| 43ec90c8-cdeb-4c5a-b71b-25ab1a03c6db | external_subnet     | 10.19.184.0/24   | {"start": "10.19.184.180", "end": "10.19.184.200"}    |
| 23e12754-0acd-4048-8981-59dfa94742cf | internal_api_subnet | 10.19.94.0/24    | {"start": "10.19.94.10", "end": "10.19.94.200"}       |
| dc35b294-069a-4206-8e20-03464f9dd632 | storage_mgmt_subnet | 192.168.200.0/24 | {"start": "192.168.200.10", "end": "192.168.200.200"} |
| c8766472-5027-4466-b96a-e96d65f636c8 | tenant_subnet       | 192.168.150.0/24 | {"start": "192.168.150.10", "end": "192.168.150.200"} |
| f273ff74-6042-4834-8a9b-8071d43f751d |                     | 192.168.0.0/24   | {"start": "192.168.0.5", "end": "192.168.0.24"}       |
++ neutron subnet-list
++ awk '{print $2}'
++ grep start
+ neutron subnet-delete c8766472-5027-4466-b96a-e96d65f636c8 ad30e2c9-8ce8-43bf-9c00-8441328237be 43ec90c8-cdeb-4c5a-b71b-25ab1a03c6db 23e12754-0acd-4048-8981-59dfa94742cf dc35b294-069a-4206-8e20-03464f9dd632 f273ff74-6042-4834-8a9b-8071d43f751d
Unable to complete operation on subnet c8766472-5027-4466-b96a-e96d65f636c8. One or more ports have an IP allocation from this subnet.
[2016-01-06 15:03:03,209] (os-refresh-config) [ERROR] during post-configure phase. [Command '['dib-run-parts', '/usr/libexec/os-refresh-config/post-configure.d']' returned non-zero exit status 1]

[2016-01-06 15:03:03,210] (os-refresh-config) [ERROR] Aborting...
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib/python2.7/site-packages/instack_undercloud/undercloud.py", line 582, in install
    _run_orc(instack_env)
  File "/usr/lib/python2.7/site-packages/instack_undercloud/undercloud.py", line 512, in _run_orc
    _run_live_command(args, instack_env, 'os-refresh-config')
  File "/usr/lib/python2.7/site-packages/instack_undercloud/undercloud.py", line 343, in _run_live_command
    raise RuntimeError('%s failed. See log for details.' % name)
RuntimeError: os-refresh-config failed. See log for details.
Command 'instack-install-undercloud' returned non-zero exit status 1



Expected result:
Successful undercloud deployment.