Modify assert technique so test passes

Future tasks is to dig into self.assertRedirectsTo wouldn't work with the test
as it stands

tests/functional/checkout/guest_checkout_tests.py

@@ -356,7 +356,9 @@ class TestPaymentDetailsView(CheckoutMixin, WebTestCase):
         mock_method.side_effect = e
         preview = self.ready_to_place_an_order(is_guest=True)
         bank_redirect = preview.forms['place_order_form'].submit()
-        assert bank_redirect.location == bank_url
+
+        assert bank_redirect.status_code == 302
+        assert bank_redirect.url == bank_url
 
     @mock.patch('oscar.apps.checkout.views.PaymentDetailsView.handle_payment')
     def test_handles_anticipated_payments_errors_gracefully(self, mock_method):