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What I found in the archive is this thread (sorry for the non-python.org URL):
In that discussion, this issue is raised, but I don't see any resolution that answers the objection made in issue 2451. Anyway, apologies in advance if there was a decision here that takes account of the above objection.
The solution to the problem John descibes WAS decided back at the time of discussion of the contribution, but for some reason, that solution never made into contribution that was committed.
The solution is simple, as described on the bug that John created for this issue.