assigning port to instance gives 401 from nova

I'm trying to create an instance with a floating IP, and heat fails.

My template is as follows:
---
heat_template_version: 2014-10-16

description: Illustration to create a single instance with a floating ip.

resources:
  instance_1_port:
    type: OS::Neutron::Port
    properties:
      network: wts-net-01
      security_groups:
        - default

  instance_1:
    type: OS::Nova::Server
    properties:
      image: "Ubuntu 14.04"
      flavor: m1.small
      key_name: harm-at-manbearpig
      networks:
# - port: { get_resource: instance_1_port }
         - network: wts-net-01

  floating_ip:
    type: OS::Neutron::FloatingIP
    properties:
      floating_network: world

  floating_ip_assoc:
    type: OS::Neutron::FloatingIPAssociation
    properties:
      floatingip_id: { get_resource: floating_ip }
      port_id: { get_resource: instance_1_port }

outputs:
  instance_1_name:
    description: Name of instance
    value: { get_attr: [instance_1, name] }
  instance_ip:
    description: External floating IP
    value: { get_attr: [floating_ip, floating_ip_address] }
---

Now when using it as the above, all goes well and everything is created just fine (though without floatingip mapping). When I replace the instance_1 networks: part to use the specified port I receive an error from nova, which originates from Neutron:

2015-03-12 20:04:30.838 30609 INFO heat.engine.stack [-] Stack CREATE FAILED (test-setup): Resource CREATE failed: ClientException: The server has either erred or is incapable of performing the requested operation. (HTTP 500) (Request-ID: req-b138a707-c348-411f-88b8-d954428defc4)
2015-03-12 20:04:30.845 30609 INFO heat.engine.service [-] Stack create failed, status FAILED

2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack rv = f(*args, **kwargs)
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack File "/usr/lib/python2.7/site-packages/nova/compute/api.py", line 1447, in create
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack check_server_group_quota=check_server_group_quota)
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack File "/usr/lib/python2.7/site-packages/nova/compute/api.py", line 1069, in _create_instance
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack max_count)
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack File "/usr/lib/python2.7/site-packages/nova/compute/api.py", line 804, in _validate_and_build_base_options
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack pci_request_info, requested_networks)
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack File "/usr/lib/python2.7/site-packages/nova/network/neutronv2/api.py", line 750, in create_pci_requests_for_sriov_ports
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack context, neutron, request_net.port_id)
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack File "/usr/lib/python2.7/site-packages/nova/network/neutronv2/api.py", line 723, in _get_port_vnic_info
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack fields=['binding:vnic_type', 'network_id']).get('port')
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack File "/usr/lib/python2.7/site-packages/nova/network/neutronv2/__init__.py", line 84, in wrapper
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack ret = obj(*args, **kwargs)
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack File "/usr/lib/python2.7/site-packages/neutronclient/v2_0/client.py", line 98, in with_params
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack ret = self.function(instance, *args, **kwargs)
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack File "/usr/lib/python2.7/site-packages/neutronclient/v2_0/client.py", line 317, in show_port
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack return self.get(self.port_path % (port), params=_params)
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack File "/usr/lib/python2.7/site-packages/nova/network/neutronv2/__init__.py", line 84, in wrapper
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack ret = obj(*args, **kwargs)
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack File "/usr/lib/python2.7/site-packages/neutronclient/v2_0/client.py", line 1320, in get
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack headers=headers, params=params)
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack File "/usr/lib/python2.7/site-packages/nova/network/neutronv2/__init__.py", line 84, in wrapper
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack ret = obj(*args, **kwargs)
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack File "/usr/lib/python2.7/site-packages/neutronclient/v2_0/client.py", line 1297, in retry_request
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack headers=headers, params=params)
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack File "/usr/lib/python2.7/site-packages/nova/network/neutronv2/__init__.py", line 84, in wrapper
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack ret = obj(*args, **kwargs)
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack File "/usr/lib/python2.7/site-packages/neutronclient/v2_0/client.py", line 1232, in do_request
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack self.httpclient.authenticate_and_fetch_endpoint_url()
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack File "/usr/lib/python2.7/site-packages/neutronclient/client.py", line 150, in authenticate_and_fetch_endpoint_url
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack self.authenticate()
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack File "/usr/lib/python2.7/site-packages/neutronclient/client.py", line 247, in authenticate
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack self._authenticate_keystone()
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack File "/usr/lib/python2.7/site-packages/neutronclient/client.py", line 226, in _authenticate_keystone
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack allow_redirects=True)
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack File "/usr/lib/python2.7/site-packages/neutronclient/client.py", line 136, in _cs_request
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack raise exceptions.Unauthorized(message=body)
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack Unauthorized: {"error": {"message": "The request you have made requires authentication.", "code": 401, "title": "Unauthorized"}}
2015-03-12 20:04:29.666 1993 TRACE nova.api.openstack