Remember, it's not just about the model "knowing" something. It's about the frame of mind it's in, if I may extend a metaphor. Including git diff in the prompt doesn't just teach it about git diff, it makes it more likely to use it.

A lot of this is obsolete with newer models, but funnily enough, the newer models don't know that - their theory of mind is at least partially obsolete in itself, so they continue to do the old "you are a software architect, don't make mistakes" prompt style.