[issue7686] redundant open modes 'rbb', 'wbb', 'abb' no longer work on Windows

[Skip Montanaro]

Changes by Skip Montanaro <skip at pobox.com>:


----------
nosy: +skip.montanaro

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue7686>
_______________________________________