I would say if anything can go in after rc2 at all, this should be accepted.  George?

I ran a few sanity checks with the patch applied:

>>> set(struct.__all__) - set(dir(struct))
set()
>>> set(dir(struct)) - set(struct.__all__)
{'_clearcache', '__all__', '__builtins__', '__file__', '__package__', '__cached__', '__name__', '__doc__'}
>>> len(set(struct.__all__)) == len(struct.__all__)
True

LGTM.  Maybe one of the tests above can be converted to a unit test.