PyObject_CallMethod is actually returning a
non-NULL result for sys.std{out,err}, and 
PyErr_Clear() isn't being run in flush_io.

The problem is deeper.  PyErr is being
used during unexceptional processing in
typeobject.c:slot_tp_getattr_hook() to
indicate that PyObject_GenericGetAttr() failed
and the __getattr__ method (used in IDLE) 
should be called.

Perhaps PyErr should be preserved in
slot_tp_getattr_hook(), instead.  Is this 
possibly a potential 2.6 issue for some uses
of getattr?  Or is the current solution 'good 
enough'?

ref issue1400.