How far should you edit your question instead of posting a new one?

Question

I posted an answer to this question, originally about the Apache Tomcat thread pool; after providing my assistance and helping the OP understand his problem, he's edited his question so my answer now appears almost unrelated.

Should the OP do this? I now feel less likely to get any up-votes/and more likely to actually be down-voted for not answering his direct "question."

What's the correct approach in such cases?

• Should I update my answer again (and again...)?
• Should I delete my answer because it's not really relevant any more (and to avoid -1's)?
• Should the question be rolled back (and the OP ask the follow up question)?
• Should it just be left as-is?

---

Update

To further explain my example to Cody Gray:

Say you have a question titled: "Car Engine Problem" then the content "How to change oil?", then someone answers:

Undo the drain plug on the engine sump to let the oil out. {snip} Lift the bonnet (hood), look for a filler cap on the engine and dip stick {snip}

Then the OP changes the title to "Gearbox issue".

Now someone views the question and thinks "Hey, you don't fill the gearbox oil at the engine filler, plus you'd usually have to be under the car - not in the engine component" - so they downvote. Whereas the answer was correct - maybe worth an upvote, now it looks totally wrong.

Answer 1

In this case, the title and the tags were changed. The body of the question didn't change; this means that the question is not different from how it was before, and the answers that were given before are still valid. The fact he changed the title could help him to direct the question to the users who know the question, but that is not an essential change to the question.

If you feel that your answer doesn't suit the question anymore, you can delete it. As far as I can see, I don't see any reason why you would get any down-vote, or why you should delete your answer.