Shared object destruction: docs and historical behavior

[Mike Pomraning]

The threads::shared POD warns:

    [A shared] object's destructor may get called multiple times, once
for each thread's scope exit.

Is this caution still accurate?

Beginning with perl 5.8.9 / threads 1.71 / threads::shared 1.27 I
cannot reproduce the behavior.  (5.8.8 does destroy objects multiple
times for me, however.)

-Mike