nothing. but tomorrow, when you are used to type git pull, you will run it on a branch with changes and you have no idea if it will rebase, merge, fast forward.

nothing. but tomorrow, when you are used to type git pull, you will run it on a branch with changes and you have no idea if it will rebase, merge, fast forward... and /then/ you will see the problem. (and open yet another stackoverflow question on how to undo the last merge :)