Suggestion for terminology "once-compatible" packages

[mpacer]

The term would refer to packages that at one time were compatible with Python 2 and Python 3, that are migrating to Python 3 only compatibility in a new release.

Basically, this is the specific use case that this is trying to address.

Also, (bonus, not a reason per se) it carries a nice allusions to other Arthurian tales (specifically, The Once and Future King).

[takluyver]

I like the story-like connotations of 'once', but I wonder if 'previously' might be clearer to non-native speakers.

[takluyver]

We should certainly explain the term before we begin using it, in any case.