How to create a bridge interface using a NIC bond

The following setup works fine on a Debian Lenny system. Notice also that the same setup on a Ubuntu 9.04 server causes a kernel panic!

The machine is a SUN blade server with two NICs. Each NIC is connected to a different switch in a redundant manner. These are the contents of the /etc/network/interfaces file:

auto lo
iface lo inet loopback

auto bond0
iface bond0 inet manual
slaves eth0 eth1
bond_mode active-backup

auto br0
iface br0 inet static
address 192.168.11.20
netmask 255.255.255.0
network 192.168.11.0
broadcast 192.168.11.255
gateway 192.168.11.1
bridge_ports bond0