Right, but none of those changes can be merged upstream, because there are too many systems where "python2" does not exist (but some python2.x does). It was a royal PITA for anybody with build scripts written in Python: do you break your scripts for Arch, or do you break them for everybody else?
OTOH, it seems to have made Arch packagers above-average aware of the problem space. I ship a reasonably popular Linux desktop application that bundles a Python scripting interface and a set of scripts using it (altogether a minor feature of the application), and when we ported that code to Python 3 in a way that keeps it running on 2.7+ back in 2011, the Arch packager dutifully dropped their patch, making Arch the only distro to run it against Python 3. I'm not used to packagers who actually read release changelogs and/or dutifully drop redundant downstream customizations without explicit reminders, so that impressed me positively :).
