Running z.py in the attached archive should produce an
attribute error on printing, as we have set sys.stdout
to None.  On 2.3.5 and 2.4.3, output is printed and any
imported C modules in x/y.py are reloaded, builtin or
3rd party.

On 2.5, we get a traceback on import: "SystemError:
Parent module 'x' not loaded".

Changing the name on the import from 'x.y' to 'y'
works-around the error, and we get the expected
AttributeError in 2.3, 2.4.  2.5 gives us the same
SystemError.