The problem with dealing directly with the positioning example is that my argument is completely semantic, I'm basically saying 'maybe the user really did mean for it to be a completely fresh version, and just ignore the history'. Which is basically an argument in favor of fuzzy matches in general. Examples where there's a lot more editing in the interim make it much more likely that the user really didn't follow all the line moves and simply wants the fuzzy match.
My point here is about the higher-level thesis - that consistent merges are just plain impossible. An argument can be made for it in the line ordering case as well, but it's a weaker one, hence my use of just this example.