[maxerickson]

The deprecate-warn-remove pattern seems to work well enough for smaller changes.

So maybe it's only when you want to do something as invasive as switching the default string type that things go so sideways, if that is even the right description for Python 3 (which I think you could argue was really about having a better language available in 2015 or 2016 or so, not just being the Python after 2.7).