I think this kind of thing needs to be decided on a case-by-case basis.
Of course, plagiarism is totally not OK and I think it's important to think carefully about how to be respectful and avoid treading on other users' toes.
In general, if I miss something from my answer and another answer includes it, I will upvote the other answer and either, leave the situation alone, or, especially if the information is really critical and cannot be left out, or there is another good reason to do so, add a link to the other answer in my own answer with something like "see answer by @AwesomePerson which explains such-and-such"
In this case, I have edited your answer as I think it made a valuable contribution but needed some clarification. I added the information you mentioned and upvoted both your post and sudodus'. I think that was an appropriate action in this case, but others may disagree with me.
Oh, and please don't use backticks for emphasis ;)