Remove these lines which are not needed.

cloudinit/distros/__init__.py

@@ -41,8 +41,6 @@ LOG = logging.getLogger(__name__)
 
 class Distro(object):
     __metaclass__ = abc.ABCMeta
-    default_user = None
-    default_user_groups = None
     hosts_fn = "/etc/hosts"
     ci_sudoers_fn = "/etc/sudoers.d/90-cloud-init-users"
     hostname_conf_fn = "/etc/hostname"