ovs: port not associated with the right bridge

I'm attempting to use Quantum with the OVS plugin to hook up some instances to existing physical networks. On my nova-compute host, eth1 is the physical network I want to bridge things onto.

In ovs_quantum_plugin.ini, I have:
network_vlan_ranges=eth1
bridge_mappings=eth1:br-site

In nova.conf, I have:
libvirt_use_virtio_for_bridges=True
libvirt_vif_driver=nova.virt.libvirt.vif.LibvirtHybridOVSBridgeDriver

I have created a br-site and added eth1 to it:
compute# ovs-vsctl list-ifaces br-site
eth1
phy-br-site

On the controller, I have defined a provider network backed by the "eth1" physical network:
controller# quantum net-show f2946abb-d5c6-4926-94c2-39ece4e6820f
+---------------------------+--------------------------------------+
| Field | Value |
+---------------------------+--------------------------------------+
| admin_state_up | True |
| id | f2946abb-d5c6-4926-94c2-39ece4e6820f |
| name | site-net |
| provider:network_type | flat |
| provider:physical_network | eth1 |
| provider:segmentation_id | |
| router:external | True |
| shared | True |
| status | ACTIVE |
| subnets | f921585c-3af9-4331-a943-119f9e5a9960 |
| tenant_id | 3138a2b60ce54a3eab33f1cbdec5b3e8 |
+---------------------------+--------------------------------------+

and associated a subnet:
controller# quantum subnet-show f921585c-3af9-4331-a943-119f9e5a9960
+------------------+----------------------------------------------------+
| Field | Value |
+------------------+----------------------------------------------------+
| allocation_pools | {"start": "10.238.158.66", "end": "10.238.158.94"} |
| cidr | 10.238.158.64/27 |
| dns_nameservers | |
| enable_dhcp | False |
| gateway_ip | 10.238.158.65 |
| host_routes | |
| id | f921585c-3af9-4331-a943-119f9e5a9960 |
| ip_version | 4 |
| name | isa-site |
| network_id | f2946abb-d5c6-4926-94c2-39ece4e6820f |
| tenant_id | 3138a2b60ce54a3eab33f1cbdec5b3e8 |
+------------------+----------------------------------------------------+

This is how I'm launching the instance:
controller# quantum port-create --fixed-ip subnet_id=f921585c-3af9-4331-a943-119f9e5a9960,ip_address=10.238.158.85 site-net
Created a new port:
[...]
| fixed_ips | {"subnet_id": "f921585c-3af9-4331-a943-119f9e5a9960", "ip_address": "10.238.158.85"} |
| network_id | f2946abb-d5c6-4926-94c2-39ece4e6820f

controller# nova boot --image 0c413854-e943-458d-8796-7b7dbb3fe581 --flavor m1.tiny --nic port-id=992402d9-e354-45f1-bcb3-d20b17a06439 petef3

Now when I go look on the compute node, I see the bridge hooked up to br-int:
compute# ovs-vsctl list-ports br-int
int-br-site
qvo992402d9-e3
tap375395d4-6f
compute# ovs-vsctl list-ports br-site
eth1
phy-br-site

But they never get hooked up to br-site, hence never get bridged to eth1, and don't end up on the network. Any ideas? Thanks in advance.