>  time.tzset() should be implemented

I'm not sure of what you mean. The function is implemented:

static PyObject *
time_tzset(PyObject *self, PyObject *unused)
{
    PyObject* m;

    m = PyImport_ImportModuleNoBlock("time");
    if (m == NULL) {
        return NULL;
    }

    tzset();

    /* Reset timezone, altzone, daylight and tzname */
    if (init_timezone(m) < 0) {
         return NULL;
    }
    Py_DECREF(m);
    if (PyErr_Occurred())
        return NULL;

    Py_RETURN_NONE;
}