Dries opened a 9.x branch, but it's not possible to filter issues by 9.x, which makes it impossible to see which issues have been moved there. We need to be able to move issues to 9.x without them getting 'lost', and there's bound to be some, er, negotiation, of what exactly is and isn't too late to go into 8.x which usually involves a bit of version changing.
See the error on:
I have a feeling we need a dev release of 9.x in order to have this available in the filters? It seems a bit like a project bug that you can file issues against a version without being able to filter on them but leaving this against core for working around it.