bind9 refusing NOTIFY msgs from designate-worker

[Murali Annamneni]

Testing with stable/queens, I see following logs from designate_backend_bind9 logs -

12-Jul-2018 19:00:45.252 received control channel command 'addzone sample.openstack.org { type slave; masters { 10.196.239.18 port 5354;}; file "slave.sample.openstack.org.3c472beb-066f-4e13-bf73-7b43ac4a61a9"; };'
12-Jul-2018 19:00:45.254 zone sample.openstack.org added to view _default via addzone
12-Jul-2018 19:00:45.285 client 10.196.239.14#44581: received notify for zone 'sample.openstack.org'
12-Jul-2018 19:00:45.285 zone sample.openstack.org/IN: refused notify from non-master: 10.196.239.14#44581
12-Jul-2018 19:00:45.500 zone sample.openstack.org/IN: Transfer started.
12-Jul-2018 19:00:45.501 transfer of 'sample.openstack.org/IN' from 10.196.239.18#5354: connected using 10.196.239.18#52668
12-Jul-2018 19:00:45.713 zone sample.openstack.org/IN: transferred serial 1531418444
12-Jul-2018 19:00:45.713 transfer of 'sample.openstack.org/IN' from 10.196.239.18#5354: Transfer completed: 1 messages, 3 records, 130 bytes, 0.211 secs (616 bytes/sec)

named.conf
---------
include "/etc/rndc.key";
options {
        listen-on port 53 { 10.196.239.18; };
        directory "/var/lib/named";
        allow-new-zones yes;
        dnssec-validation auto;
        auth-nxdomain no;
        request-ixfr no;
        recursion no;
        minimal-responses yes;
        allow-notify { 10.196.239.14;10.196.239.15; };
};

controls {
        inet 10.196.239.18 port 953 allow { 10.196.239.14; 10.196.239.15; } keys { "rndc-key"; };
};

pools.yaml
---------
- name: default-bind
  id: 3e0da616-e465-46bc-8a80-ff4c8857746f
  description: Default BIND9 Pool
  attributes: {}
  ns_records:
    - hostname: sample.openstack.org.
      priority: 1
  nameservers:
    - host: 10.196.239.18
      port: 53
  targets:
    - type: bind9
      description: BIND9 Server 10.196.239.18
      masters:
        - host: 10.196.239.18
          port: 5354
      options:
        host: 10.196.239.18
        port: 53
        rndc_host: 10.196.239.18
        rndc_port: 953
        rndc_key_file: /etc/designate/rndc.key