The patch implements PEP 349: "Allow str() to return
unicode strings".  The backwards compatibility problems
appear to be rare.  Hopefully more people can test
their applications.  I'm not very happy with the new
function named PyString_New since it really belongs in
Python/object.c, not stringobject.c.  However, I can't
think of a better name.  I think it should be made
available to extension modules somehow so _PyObject_Str
is no good.