That's precisely what's happening with the third-party Python2 forks. The renaming of Perl 6 occurred last October, specifically because of the problems caused

That's precisely what's happening with the third-party Python2 forks. The renaming of Perl 6 occurred last October, specifically because of the problems caused by the confusion between the incompatible Perl 5 and 6 that caused a lot of trouble to the Perl people on either side for many years. It's not a mirrored parallel, it's the Python folks learning from Perl's mistakes and making sure that this parallel won't come to be.