It seems to me, that all builtin and extension types set tp_free to PyObject_Del, PyObject_GC_Del, or 0. The int class is the only exception.

int_free() was introduced in 200559fcc664:

> Make sure that tp_free frees the int the same way as tp_dealloc would.
> This fixes the problem that Barry reported on python-dev:
>    >>> 23000 .__class__ = bool
> crashes in the deallocator.  This was because int inherited tp_free
> from object, which uses the default allocator.

The above example no longer works:

>>> 23000 .__class__ = bool
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: __class__ assignment: only for heap types

I think int_free should be removed and tp_free should be reverted to 0 (as in float type).