Why does 'Pull' perform a 'git fetch' followed by a 'git pull', instead of a 'git fetch' followed by 'git merge/rebase', or just 'git pull' without a redundant first fetch (since 'git pull' is just a short cut for fetch+merge..)?
It seems that requiring two round trips to the server instead of just one would be worse for performance, so is there something additional that the initial 'git fetch' accomplishes?