[Python-3000] Build is broken (r55196)

[Collin Winter]

As of r55196 (and possibly earlier), the p3yk branch does not make
when configured with --with-pydebug. setup.py triggers this assertion
failure:

python: Objects/object.c:64: _Py_AddToAllObjects: Assertion
`(op->_ob_prev == ((void *)0)) == (op->_ob_next == ((void *)0))'
failed.

Any ideas?