Bug in code dispatching based on internal slots

Objects/typeobject.c

 /* Type object implementation */
 
 #include "Python.h"
 #include "frameobject.h"
 #include "structmember.h"
 
 #include <ctype.h>
 
 
 /* Support type attribute cache */
@@ skipping 5448 matching lines @@
     ETSLOT(NAME, as_number.SLOT, FUNCTION, wrap_binaryfunc_l, \
            "x." NAME "(y) <==> " DOC)
 #define RBINSLOTNOTINFIX(NAME, SLOT, FUNCTION, DOC) \
     ETSLOT(NAME, as_number.SLOT, FUNCTION, wrap_binaryfunc_r, \
            "x." NAME "(y) <==> " DOC)
 
 static slotdef slotdefs[] = {
     SQSLOT("__len__", sq_length, slot_sq_length, wrap_lenfunc,
            "x.__len__() <==> len(x)"),
     /* Heap types defining __add__/__mul__ have sq_concat/sq_repeat == NULL.
-       The logic in abstract.c always falls back to nb_add/nb_multiply in
-       this case.  Defining both the nb_* and the sq_* slots to call the
-       user-defined methods has unexpected side-effects, as shown by
-       test_descr.notimplemented() */
+       The logic in abstract.c ignores them if nb_add/nb_multiply are
+       defined anyway. */
     SQSLOT("__add__", sq_concat, NULL, wrap_binaryfunc,
       "x.__add__(y) <==> x+y"),
     SQSLOT("__mul__", sq_repeat, NULL, wrap_indexargfunc,
       "x.__mul__(n) <==> x*n"),
     SQSLOT("__rmul__", sq_repeat, NULL, wrap_indexargfunc,
       "x.__rmul__(n) <==> n*x"),
     SQSLOT("__getitem__", sq_item, slot_sq_item, wrap_sq_item,
            "x.__getitem__(y) <==> x[y]"),
     SQSLOT("__setitem__", sq_ass_item, slot_sq_ass_item, wrap_sq_setitem,
            "x.__setitem__(i, y) <==> x[i]=y"),
@@ skipping 898 matching lines @@
     0,                                          /* tp_base */
     0,                                          /* tp_dict */
     super_descr_get,                            /* tp_descr_get */
     0,                                          /* tp_descr_set */
     0,                                          /* tp_dictoffset */
     super_init,                                 /* tp_init */
     PyType_GenericAlloc,                        /* tp_alloc */
     PyType_GenericNew,                          /* tp_new */
     PyObject_GC_Del,                            /* tp_free */
 };