[Pyrex] bug if exception is being generated in pyrex constructor

[Greg Ewing]

Gustavo Sverzut Barbieri wrote:
> Attached is a test case that shows pyrex generated extension type
> segfaulting if it inherits from a class that raised an exception in
> its constructor.

Doing something inside a C-level constructor which could
raise an exception is a dangerous thing to do in the first
place, since a partly-constructed object can cause all
sorts of trouble when its destructor is executed.

I'll see if I can do something about this particular
manifestation of the problem, though.

Thanks,
Greg