If allowed by the configuration, this returns the set of permissions
        defined by the user's LDAP group memberships.

def get_group_permissions(self):
        """
        If allowed by the configuration, this returns the set of permissions
        defined by the user's LDAP group memberships.
        """
        if self._group_permissions is None:
            self._group_permissions = set()

            if self.settings.FIND_GROUP_PERMS:
                try:
                    self._load_group_permissions()
                except ldap.LDAPError as e:
                    results = ldap_error.send(self.backend.__class__,
                                              context='get_group_permissions',
                                              exception=e)
                    if len(results) == 0:
                        logger.warning("Caught LDAPError loading group permissions: %s",
                                       pprint.pformat(e))

        return self._group_permissions