Python 2.6 bug with IOError in a context manager

demonstrate_py26_bug.py

#!/usr/bin/env python
from __future__ import print_function

class Context(object):
    def __enter__(self):
        yield
    def __exit__(self, type, value, tracebck):
        print("type: {0}".format(str(type(value))))
        print("repr: {0}".format(repr(value)))
        print("istuple: {0}, isioerror: {1}".format(isinstance(value, tuple), isinstance(value, IOError)))
        # Silence any exceptions
        return True

# Feel free to replace /etc/shadow with any file the current user doesn't
# have read access to
with Context():
    fh = open('/etc/shadow')

gistfile1.sh

[jeff@omniscience ~]$ for ver in 2.{6,7} 3.4; do
> echo testing python${ver}
> python${ver} demonstrate_py26_bug.py
> done
testing python2.6
type: (13, 'Permission denied', '/etc/shadow')
repr: (13, 'Permission denied', '/etc/shadow')
istuple: True, isioerror: False
testing python2.7
type: [Errno 13] Permission denied: '/etc/shadow'
repr: IOError(13, 'Permission denied')
istuple: False, isioerror: True
testing python3.4
type: [Errno 13] Permission denied: '/etc/shadow'
repr: PermissionError(13, 'Permission denied')
istuple: False, isioerror: True