Traceback (most recent call last):
  File "/usr/bin/vmbuilder", line 24, in <module>
    cli.main()
  File "/usr/lib/python2.6/dist-packages/VMBuilder/contrib/cli.py", line 62, in main
    hypervisor, distro = self.handle_args(optparser, sys.argv[1:])
  File "/usr/lib/python2.6/dist-packages/VMBuilder/contrib/cli.py", line 173, in handle_args
    hypervisor = VMBuilder.get_hypervisor(args[0])(distro)
  File "/usr/lib/python2.6/dist-packages/VMBuilder/hypervisor.py", line 34, in __init__
    super(Hypervisor, self).__init__()
  File "/usr/lib/python2.6/dist-packages/VMBuilder/distro.py", line 30, in __init__
    super(Context, self).__init__(self)
  File "/usr/lib/python2.6/dist-packages/VMBuilder/plugins/__init__.py", line 46, in __init__
    self.register_options()
  File "/usr/lib/python2.6/dist-packages/VMBuilder/plugins/virtualbox/vm.py", line 36, in register_options
    group.add_option('--vbox-disk-format', metavar='FORMAT', default='vdi', help='Desired disk format. Valid options are: vdi vmdk. [default: %default]')
AttributeError: 'SettingGroup' object has no attribute 'add_option'