Git1.8の頃から次のメジャーバージョンアップで変わるよ！って言われているのは知ってたけど1.9じゃなくて2.0なのか次は。
Backward compatibility notes (for Git 2.0) ------------------------------------------ When "git push [$there]" does not say what to push, we have used the traditional "matching" semantics so far (all your branches were sent to the remote as long as there already are branches of the same name over there). In Git 2.0, the default will change to the "simple" semantics that pushes the current branch to the branch with the same name, only when the current branch is set to integrate with that remote branch. There is a user preference configuration variable "push.default" to change this. If you are an old-timer who is used to the "matching" semantics, you can set it to "matching" to keep the traditional behaviour. If you want to live in the future early, you can set it to "simple" today without waiting for Git 2.0.https://github.com/git/git/blob/master/Documentation/RelNotes/1.8.3.txt
