@classmethod
    def _check_for_deployed_nodes(cls, cluster):
        env_version = cluster.release.environment_version
        if not StrictVersion(env_version) >= StrictVersion('8.0'):
            if any(objects.Cluster.get_nodes_by_status(
                    cluster,
                    consts.NODE_STATUSES.ready)):
                raise errors.NotAllowed(
                    "Reconfiguration of nodes after the "
                    "deployment is allowed only for "
                    "environments 8.0 or greater."
                )
Test save signals for proxy models
dataset/ETHPy150Open openstack/fuel-web/nailgun/nailgun/api/v1/validators/node_group.py/NodeGroupValidator._check_for_deployed_nodes--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.5/tests/modeltests/proxy_models/tests.py/ProxyModelTests.test_proxy_model_signals