A few days ago, I encountered frustrating behavior with hashset where hash is not defined for arbitrary ref objects, which as [pointed out by Araq a few years ago](https://forum.nim-lang.org/t/7765#49360) (pre 2.0) is "a strange omission". The functionality has since been added behind a compiler flag, and from what I can tell it seems like it's seen as the more sensible default.
Given this, I was surprised to learn the change and flag were added 3 years ago and weren't moved to become default with 2.0. Do we maintain a list of breaking changes we want to make? Is there a reason this wasn't included?
