[Python-3000] Need help fixing failing Py3k Unittests in py3k-struni

[Christian Heimes]

I found a bug in the str type that may affect a lot of tests.

In the py3k-struni branch the str() constructor doesn't use __str__ when
the argument is an instance of a subclass of str. A user defined string
can't change __str__(). The __repr__ method isn't affected.

It works in Python 2.5 and in the p3yk branch.

Python 3.0x (py3k-struni:56245, Jul 10 2007, 23:34:56)
[GCC 4.1.2 (Ubuntu 4.1.2-0ubuntu4)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> class Mystr(str):
...     def __str__(self): return 'v'
...
>>> s = Mystr('x')
>>> s
'x'
>>> str(s)
'x' # <- SHOULD RETURN 'v'

Christian