[raring] No ip assigned to bridge and no routes added for virtual networks

I migrated network configuration from my 12.04 LTS host:
<network connections='1'>
  <name>vm100</name>
  <uuid>38ffbbe2-0e06-4233-b7c7-1f672401d434</uuid>
  <forward dev='eth0' mode='route'>
    <interface dev='eth0'/>
  </forward>
  <bridge name='virbr1' stp='on' delay='0' />
  <mac address='52:54:00:B7:10:21'/>
  <ip address='192.168.100.1' netmask='255.255.255.0'>
    <dhcp>
      <range start='192.168.100.2' end='192.168.100.254' />
    </dhcp>
  </ip>
</network>

Upon defining and start virbr1 is created but it has no IP address, subsequently there are no IP routes to the network. After adding the ip address and routes to the interface my machine (naturally) started to be able to communicate with the world.

I feel this is a regression since there was no additional configuration involved with 12.04 to get this up and running.

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: libvirt-bin 1.0.0-0ubuntu4
ProcVersionSignature: Error: [Errno 2] No such file or directory: '/proc/version_signature'
Uname: Linux 3.8.0-030800rc2-generic x86_64
ApportVersion: 2.8-0ubuntu1
Architecture: amd64
Date: Sun Jan 13 19:31:17 2013
InstallationDate: Installed on 2013-01-04 (9 days ago)
InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Alpha amd64 (20130104)
MarkForUpload: True
SourcePackage: libvirt
UpgradeStatus: No upgrade log present (probably fresh install)