While reading the source I saw that recent py3k has this in Objects/object.c (reasonably recent trunk has it as well):

#if 0 /* XXX this is not quite _PyType_Lookup anymore */
    /* Inline _PyType_Lookup */
    { ... removed ...
    }
#else
    descr = _PyType_Lookup(tp, name);
#endif

This was commented out (on trunk, I assumed on py3k it was for the same reason) by amaury.forgeotdarc on revision 59943, when a patch to the real _PyType_Lookup was applied.

I think it can be safely removed.