Created attachment 222418 [details] patch
Looks good to me, does it apply other versions of python?
(In reply to Li-Wen Hsu from comment #1) Yeah, but I thought I'd just do it for 3.9 to be on the safe side.
(In reply to Steve Wills from comment #2) Maybe we can apply to all versions of python, but only enable it by default on 3.9 first?
*** This bug has been marked as a duplicate of bug 253604 ***