"RecordSet not found" while trying to update NS Pool

[Vladimir Grevtsev]

Version: stable/liberty
Steps to reproduce:

1) Get an actual NS pool list (to acquire its ID)

$ http http://designate.int.zone:9001/v2/pools
HTTP/1.1 200 OK
Connection: keep-alive
Content-Length: 504
Content-Type: application/json; charset=UTF-8
Date: Sun, 15 Nov 2015 08:45:44 GMT
X-Openstack-Request-Id: req-c010ef2a-31d8-45a7-bbbc-a8c904283a21

{
    "links": {
        "self": "http://designate.int.zone:9001/v2/pools"
    },
    "pools": [
        {
            "attributes": {},
            "created_at": "2015-09-24T08:31:16.000000",
            "description": null,
            "id": "794ccc2c-d751-44fe-b57f-8894c9f5c842",
            "links": {
                "self": "http://designate.int.zone:9001/v2/pools/794ccc2c-d751-44fe-b57f-8894c9f5c842"
            },
            "name": "default",
            "ns_records": [
                {
                    "hostname": "ns1.old.zone.",
                    "priority": 10
                },
                {
                    "hostname": "ns2.old.zone.",
                    "priority": 10
                }
            ],
            "project_id": null,
            "updated_at": "2015-09-24T08:31:41.000000"
        }
    ]
}

2) Try to update this NS pool

$ http --json PATCH http://designate.int.zone:9001/v2/pools/794ccc2c-d751-44fe-b57f-8894c9f5c842 ns_records:='[{"hostname": "ns1.int.zone.", "priority": 1}]'

HTTP/1.1 404 NOT FOUND
Connection: keep-alive
Content-Length: 141
Content-Type: application/json
Date: Sun, 15 Nov 2015 08:45:57 GMT
X-Openstack-Request-Id: req-ac23b1e0-7e1b-4899-8736-803edb93f6cf

{
    "code": 404,
    "message": "Could not find RecordSet",
    "request_id": "req-ac23b1e0-7e1b-4899-8736-803edb93f6cf",
    "type": "recordset_not_found"
}

3) If there are another NS records in zone(s) present - still fails, but after manual deletion of all non-managed NS records - request above is succeeded.

[Tim Simmons (timsim)]

I thought this might be a dup of https://bugs.launchpad.net/designate/+bug/1500798, looks like it's a bit different, needs more investigation.