Here's the situation- someone asks a question, accepts an answer, and then un-accepts the answer, and edits the question, making that answer and other existing answers incorrect...
I've tried to research the issue on Meta and found a few cases of this happening, the general consensus seems to be that its not appreciated and the OP should have asked a new question, but there doesn't seem to be any real mechanism or suggestion as to what to do about it.
Should these cases be flagged for an edit roll back?
Doesn't the asker have the right to modify his question?
Exit strategies for "chameleon questions"
Note- I'd rather not reference the specific case as it would likely draw a lot of negative attention to the asker, and I think keeping it broad would help in other cases.