I did not know about rounding to even, so maybe there should be a warning in the 2.7 documentation, that the behavior changed in python 3 (I just checked that: python2.7 is in line with the documentation). 

The first time I stumbled over these issues was when implementing a game, where I wanted to map pixels to hexfields, where I had to get the borderline cases right: https://bitbucket.org/ArneBab/hexbattle/src/38ad49c04836/hexgrid.py#cl-24

This likely won’t hit me in the game, but it really hurts in the doctests.

PS: I like the naming as “allow other rounding modes”, so I changed the title of the bug. I hope that’s OK.

PPS: Thank you for all your replies! The bugtracker feels really welcoming and helpful, even when reporting something as a bug, which is just a difference in goal definition. I hope it will turn out to be useful for the community!