"XXX undetected error" in python_d.exe

[Tim Peters]

[Courageous]
> ...
> In retrospect, this appears to be a case of me not knowing exactly
> when to use the PyErr_Clear() call. This simply _must_ fall into
> the domain of extension authoring esoterica. :-)

The 2.2 docs should be clearer about this, but the bottom-line rules are
simple:

1. Every C API function call capable of an error return must be
   checked for an error return.

2. When a C API function call does indicate an error occurred, you
   must either pass that error on to your caller, or, if you intend
   to ignore the error, you must call PyErr_Clear() before making
   another C API function call.

It's best not to think too hard about what those rules imply when a
destructor gets called by magic ...