File "/usr/share/openstack/cloudinstall/multi_install.py", line 373, in prompt_for_bridge
    self.configure_nat(get_network('br0'))
  File "/usr/share/openstack/cloudinstall/netutils.py", line 61, in get_network
    info = _networkinfo(interface)
  File "/usr/share/openstack/cloudinstall/netutils.py", line 32, in _networkinfo
    out = check_output(ipcmds).decode('utf-8')
  File "/usr/lib/python3.4/subprocess.py", line 616, in check_output
    raise CalledProcessError(retcode, process.args, output=output)
subprocess.CalledProcessError: Command '['ip', '-o', '-4', 'address', 'show', 'dev', 'br0']' returned non-zero exit status 1