def __deepcopy__(self, memo):
        result = super(Driver, self).__deepcopy__(memo)
        result.remove_trait('missing_deriv_policy')
        return result
For some reason `missing_deriv_policy` gets resurrected.
dataset/ETHPy150Open OpenMDAO/OpenMDAO-Framework/openmdao.main/src/openmdao/main/driver.py/Driver.__deepcopy__