Best practices when an OP edits the answered question creating an entirely new one?

Question

This question was triggered by Why do some files appear twice in Unity Dash?

After receiving an answer that was clearly correct, The OP drastically edited the original question creating in effect an entirely new question. This seems counter-intuitive to me as the end result makes it difficult if not impossible for those with the same original question to locate the correct answer to that question without asking it over again.

What I did was rollback the question to it's original state and suggest that the OP ask a new question on the topic that the answer triggered for him.

This seems the most logical approach to me. I'm looking to the community to chime in on this and provide feedback on what is perceived to be the best approach in instances such as this.

While it may not have been the OP's intent to make us less effective in our work, that's clearly the result of edits that change the question entirely rather than providing clarification on the original question. This may be a duplicate question as I'm certain this has happened before, but I couldn't find one.

Answer 1

Yep, roll it back and ask them to post a new one is the way to go. Otherwise, people have just wasted their time answering, the answers no longer make sense and the whole thing becomes a mess.

If the OP rolls your rollback back again, flag with a custom flag for mod attention.

Answer 2

In addition to flagging for mod attention, leave a comment under the question itself that the user's edit change the user's original question, hence affect the existing answer and potentially future answers. That has two effects - one of letting the OP know they're doing bad juju, and letting other answerers know that this OP is bad news bears and maybe ( just maybe ) one shouldn't rush and answer the question that potentially might change context ( and lo and behold you get downvote for answering something that originally wasn't there).