exc_value parameter from __exit__() (context manag

I tried to mess around with context managers and got a bit surprised when running my code with Python 2.6. Indeed, the exc_value parameter seems to be a string instead of an exception.

A bit of code to hi-light this issue :

import sys

class contextmanager(object):

    def __enter__(self):
        pass

    def __exit__(self, type_, value, traceback):
        assert (type_ is None) == (value is None)
        if value is not None:
            print(type(value))


if __name__ == '__main__':
    print(sys.version_info)
    with contextmanager():
        __name_ # should trigger name exception

With Python 2.7 :

<type 'exceptions.NameError'>                       # GOOD
Traceback (most recent call last):
  File "test_conman.py", line 17, in <module>
    __name_
NameError: name '__name_' is not defined

With Python 3.2 :

sys.version_info(major=3, minor=2, micro=3, releaselevel='final', serial=0)
<class 'NameError'>                       # GOOD
Traceback (most recent call last):
  File "test_conman.py", line 17, in <module>
    __name_
NameError: name '__name_' is not defined

With Python 2.6 :

(2, 6, 7, 'final', 0)
<type 'str'>                       # BAD
Traceback (most recent call last):
  File "test_conman.py", line 17, in <module>
    __name_
NameError: name '__name_' is not defined

My understanding is that exc_value should always be an exception. Is there anything I did wrong ? Is there anything I misunderstood ? Is this a known issue ?

References