@Michael.Felt can you just insert some prints between these 3 to see what is going on (and re-compile)

static void
gen_dealloc(PyGenObject *gen)
{
    PyObject *self = (PyObject *) gen;
<<<<
    _PyObject_GC_UNTRACK(gen);
<<<<
    if (gen->gi_weakreflist != NULL)
        PyObject_ClearWeakRefs(self);
<<<<
    _PyObject_GC_TRACK(self);


something like this should work: printf("%ld\n", _Py_AS_GC(self)->_gc_next);