12 years later, we finally landed your fix :).  Thanks for the patch, and for bearing with us (and me in particular for the past couple months).

As mentioned in the PR, there is probably opportunity to clean up the cleanup code in the new test a bit, and as Éric and Ammar mentioned here and in review, it could be interesting to use TextIOWrapper instead (though we'd probably only make that change in 3.9).  If you're interesting in doing a follow-up PR, it can either be attached to this issue (in spite of it being closed) or a new issue opened.