AttributeError: 'SettingGroup' object has no attribute 'add_option'

$ sudo ./build.sh
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 59, in main
    hypervisor, distro = self.handle_args(optparser, sys.argv[1:])
  File "/usr/lib/python2.6/dist-packages/VMBuilder/contrib/cli.py", line 160, in handle_args
    hypervisor = VMBuilder.get_hypervisor(args[0])(distro)
  File "/usr/lib/python2.6/dist-packages/VMBuilder/hypervisor.py", line 32, 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/xen/vm.py", line 34, in register_options
    group.add_option('--xen-kernel', metavar='PATH', help='Path to the kernel to use (e.g.: /boot/vmlinux-2.6.27-7-server). Default depends on distribution and suite')
AttributeError: 'SettingGroup' object has no attribute 'add_option'

...as the Python API changed?