I don't think that would be a real solution because it looks like that would cause the while loop always to loop at most once (which would defeat its purpose) -- because the loop ends with "o = context":

while ((context = PyException_GetContext(o))) {
    Py_DECREF(context);
    if (context == value) {
        PyException_SetContext(o, NULL);
        break;
    }
    o = context;
}