The new logic for testing against accidental breakage of previous stable Flutter releases only understands Flutter SDK constraints. This caused a problem for flutter_lints, which doesn't use a Flutter constraint at all. For now we've worked around the limitation by excluding it, but we should have a general solution; about half of the packages in flutter/packages don't have a Flutter constraint (unlike flutter/plugins, where it's pretty much universal).

We could potentially add another flag with the Dart SDK, but it might be simpler to add a Flutter->Dart version mapping in the tool. We'd have to update that occasionally, but only when a package first wants to drop a legacy version that's never been dropped before. That would be about once a quarter at most, and probably less.