Add roles names to user.roles, based on users_roles.

        :param user: user to update
        :param users_roles: list of roles ID
        :param roles_list: list of roles obtained with keystone

def _update_user_roles_names_from_roles_id(self, user, users_roles,
                                               roles_list):
        """Add roles names to user.roles, based on users_roles.

        :param user: user to update
        :param users_roles: list of roles ID
        :param roles_list: list of roles obtained with keystone
        """
        user_roles_names = [role.name for role in roles_list
                            if role.id in users_roles]
        current_user_roles_names = set(getattr(user, "roles", []))
        user.roles = list(current_user_roles_names.union(user_roles_names))