I'm sure that there has been more changes from Perl 5.8 to Perl 5.40 than there is between Python 2.0 to Python 3.x (Whatever version it is up to at the moment.)

What's more is that every change from Python 2 to Python 3 that I've heard of, resembles a change that Perl5 has had to do over the years. Only Perl did it without breaking everything. (And thus didn't need a major version bump.)