We *do* care about NotImplemented, that's the whole point of this bug report. I don't see how this is a problem in the new_total_ordering.py example. Can you give an example of when you get a stack overflow?
The examples in new_total_ordering are in themselves badly implemented, as they do check of the class with an isinstance, but if it is not the correct instance, they will return False or raise a TypeError. That's wrong, they should return NotImplemented, to give the other class a chance. But that is not a problem for the tests, it's only a problem if you use the tests as examples of how to implement a comparable class.
But in no case am I able to get a stack overflow here, which I can with the old total_ordering recipe.