IPs from dhcp disabled subnets are added to host file when multiple subnets

If a network has many subnets, and some have dhcp enabled and some don't, then ips from all subnets are added to the dnsmasq host file.

Step:
$ neutron net-create net44
$ neutron subnet-create net44 10.0.10.0/24 --name sub1 --enable_dhcp true
$ neutron subnet-create net44 10.0.20.0/24 --name sub2 --enable_dhcp false

$ neutron subnet-list --fields id --fields name
+--------------------------------------+----------------+
| id | name |
+--------------------------------------+----------------+
| 4e32d76e-4c3a-458c-a250-69856ac325c2 | sub1 |
| c5f0d5a4-227b-4f60-914f-88c6f1b03525 | sub2 |
| e2de152d-a6dc-431e-8ca4-758601161f84 | private-subnet |
+--------------------------------------+----------------+

$ neutron port-create net44 \
    --fixed-ip subnet_id=4e32d76e-4c3a-458c-a250-69856ac325c2 \
     --fixed-ip subnet_id=c5f0d5a4-227b-4f60-914f-88c6f1b03525
+-----------------------+----------------------------------------------------------------------------------+
| Field | Value |
+-----------------------+----------------------------------------------------------------------------------+
| admin_state_up | True |
| allowed_address_pairs | |
| binding:vnic_type | normal |
| device_id | |
| device_owner | |
| extra_dhcp_opts | |
| fixed_ips | {"subnet_id": "4e32d76e-4c3a-458c-a250-69856ac325c2", "ip_address": "10.0.10.2"} |
| | {"subnet_id": "c5f0d5a4-227b-4f60-914f-88c6f1b03525", "ip_address": "10.0.20.2"} |
| id | 86b2b51b-a0e3-4f74-bb7d-e76eab90c9ed |
| mac_address | fa:16:3e:c7:15:82 |
| name | |
| network_id | fab1f41e-d9a4-4ca9-bce3-bb5321822958 |
| security_groups | b572b0b9-2fe3-4651-a903-f0dfbaf1c433 |
| status | DOWN |
| tenant_id | 15a0f58023434a78a13bf44e277580ef |
+-----------------------+----------------------------------------------------------------------------------+

vagrant@devstack:~$ cat /opt/stack/data/neutron/dhcp/fab1f41e-d9a4-4ca9-bce3-bb5321822958/host
fa:16:3e:c7:15:82,host-10-0-10-2.openstacklocal,10.0.10.2
fa:16:3e:c7:15:82,host-10-0-20-2.openstacklocal,10.0.20.2