django unittest bug

[freewave@…]

enviroment: python2.7 + django1.3
with the steps below:
1、 django-admin.py startproject myapp
2、 cd myapp
3、 manage.py startapp foo
4、 manage.py test

error occurs:
File "C:\Python27\lib\site-packages\django\test\simple.py", line 237, in setup_test_environment

unittest.installHandler()

AttributeError:'module' object has no attribute 'installHandler'

problem?:
the file “site-packages\django\utils\unittest” contains the code
try:

# check the system path first
from unittest2 import *

except ImportError:

if sys.version_info >= (2,7):

# unittest2 features are native in Python 2.7
from unittest import *

else:

...

but unittest2 features are native in Python 2.7?