@MikeHoneychurch asked in chat what we should do with questions that have been tagged as [bugs] now that version 9 was released. Some of these bugs might be fixed in version 9. This post is to start a discussion for deciding this.
I propose that:
If the bug is fixed:
Tag it with version-8 only (possibly earlier if there's a special reason to do so)
Add a visible (bolded?) note in the question explaining that the bug was fixed in version 9. (I didn't propose adding an answer because many of these will already have accepted answers.) I think this information is going to be useful for people who might still be on earlier versions.
I went ahead and did this in this question: Issue with PathGraph
(A possible reason not to do this too quickly is to avoid the front page being spammed with edits.)