None of this helps you understand how merging works, of course. Pro Git is great at telling you mechanically how to merge, but doesn't explain at all what can g

None of this helps you understand how merging works, of course. Pro Git is great at telling you mechanically how to merge, but doesn't explain at all what can go wrong, and I don't think it actually describes the merge algorithm anywhere (certainly not in the main body of the book, or the section on Internals).