Arthur Lutz <arthur.lutz@logilab.fr> [Wed, 10 Feb 2016 14:43:05 +0100] rev 11103
[exceptions] fix string conversion for Unauthorized exception
changeset 3cb87b61b067 changed CubicWebException to define __unicode__
as the main entry point for string conversion, but left Unauthorized's
__str__ definition unchanged, leading to a mismatch. Closes #10646396.
Fix Binary on python < 2.7.4 (closes #10593811)
Before the fix for http://bugs.python.org/issue10211 we can't pass a
buffer object to BytesIO, so keep using StringIO in that case. And
because StringIO is an old-style class, we can't use super().