Well, I'm not sure. I didn't realize it while running python_d.exe.
I just realized it while re-reading source code.

MSDN says, (http://msdn.microsoft.com/en-us/library/ms724211%28VS.85%29.aspx)

> If the application is running under a debugger, the function will
> throw an exception if it receives either a handle value that is not
> valid or a pseudo-handle value. This can happen if you close a handle
> twice, (snip)

So if someone run python_d.exe in debugger, maybe he/she can see
exception.