time.strptime() intermittently (and I mean _really_ intermittently) throws an AttributeError.

Steps to reproduce:

Run the attached script (you may have to do this quite a lot of times; in an evening of trying, I could only trigger this bug once...) - this just starts lots of threads so that we have lots of time.strptime()'s running in parallel.

Expected:

It just keeps running every time.

Actual:

On one run, the script bailed out almost immediately -

ccorbacho@valkyrie:~/chroots/trunk/home/ccorbacho/scratch/ccorbacho$ python test_time.py
Exception in thread Thread-2:
Traceback (most recent call last):
  File "/usr/lib64/python2.6/threading.py", line 532, in __bootstrap_inner
    self.run()
  File "test_time.py", line 13, in run
    time.strptime("30 Nov 00", "%d %b %y")
AttributeError: _strptime_time

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This is with Python 2.6.6. However, at work we have been seeing this very intermittently with Python 2.5 in threaded code doing time.strptime() as well (though we just get AttributeError: strptime, but I don't have any code I can provide to reproduce on 2.5), hence I'm raising the bug.