Quoting Martin v. Löwis:
"""
I think it's pointless. If they ever be NULL, the INCRE/DECREF
will crash right away, anyway, so you'll certainly notice.
As you will have a debug build when the assertion triggers,
you can just as well fine the location of the crash quickly
in the debugger (e.g. using the core file on systems that
support that, or the JIT-debugger on other systems).
"""

Rejecting on that basis.