> Doing it after Py_CLEAR(self->mbuf) seems to contradict 
> 
>     http://docs.python.org/dev/extending/newtypes.html?highlight=pyobject_clearweakrefs#weak-reference-support
> 
> which says
> 
>     The only further addition is that the destructor needs to call the weak 
>     reference manager to clear any weak references. This should be done *before*
>     any other parts of the destruction have occurred, but is only required if the 
>     weak reference list is non-NULL:

Mmh, this seems to be misled. The original formulation is from SVN
r16381; the clearly erroneous part about resurrecting objects was later
removed in r18223, but the rest is probably unnecessary as well. I'll
open a separate issue.