@roles.setter
    def roles(self, value):
        self._roles = list(value)
        self.config_validated = False
Writes out the datastore file. Be careful! If the file already exists,
dataset/ETHPy150Open openstack/compass-core/compass/db/models.py/ClusterHost.roles--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/api/datastore_file_stub.py/DatastoreFileStub.__WriteDatastore