'Rerun test_return_type_warning with nrt'

def test_return_type_warning_with_nrt(self):

    y = np.ones(4, dtype=np.float32)
    def return_external_array():
        return y
    with warnings.catch_warnings(record=True) as w:
        warnings.simplefilter('always', NumbaWarning)
        cfunc = jit(return_external_array)
        cfunc()
        self.assertEqual(len(w), 0)
