511 static PyObject *
512 Mapping_update(PyObject *self, PyObject *seq)
513 {
514     if (update_from_seq(self, seq) < 0)
when considering range: -0x80000000 <= value <= -1
taking True path
515 	return NULL;
516     Py_INCREF(Py_None);
517     return Py_None;
518 }
returning (PyObject*)NULL without setting an exception