Git branches trying to push to master.

Question

I don't know what I changed, but recently when I try to push up one of my branches by using "git push" it tries to push to the remote branch and to master.

➜  module1 git:(my-branch) git push 
Counting objects: 40, done.
Delta compression using up to 8 threads.
Compressing objects: 100% (25/25), done.
Writing objects: 100% (40/40), 3.68 KiB | 0 bytes/s, done.
Total 40 (delta 14), reused 0 (delta 0)
To git@github.corp.company.com:Project-1/SomeProject.git
   1000000..000000e  my-branch -> my-branch
 ! [rejected]        master -> master (non-fast-forward)

Luckily each time it has happened I have gotten a rejected message because my branch has been behind master. I used to be able to just type git push, and it would only push the branch I was tracking. I have looked into my git config and it doesn't look like it should be pushing to master.

[remote "origin"]
    url = git@github.corp.company.com:Project-1/SomeProject.git
    fetch = +refs/heads/*:refs/remotes/origin/*
[branch "master"]
    remote = origin
    merge = refs/heads/master
[branch "my-branch"]
    remote = origin
    merge = refs/heads/my-branch

Any way I can prevent this from happening?

Answer 1

Configure push.default

You want to set push.default to one of simple, upstream, or current. In fact, you probably want simple.

To set simple mode for yourself, for all repositories where you have not set some other value, use:

git config --global push.default simple

To override this in one specific repository, use, e.g.:

git config push.default upstream

(assuming you want upstream mode for the current repository, regardless of your --global setting).

The "default default" depends on your version of Git.

In Git versions before 2.0, the initial default is matching. This is the behavior you are seeing now and is clearly not what you want.

In Git versions 2.0 or later, the initial default is simple. If this is what you want and git --version tells you that you have 2.0 or later, you don't have to set anything.

What simple and upstream mean

In Git, each of your branches (your local branch names, like master and my-branch) can have one "upstream" setting. (Or it can have no upstream setting, but that's not very useful to us!) The main command to set or change the upstream is git branch --set-upstream-to.

The upstream is itself essential two parts: the name of a remote, like origin, and the name of a branch on that remote, like master. With git branch --set-upstream-to you just name the remote-tracking branch, origin/master, to set both at once, and it does the obvious thing.

Once set, git push will pick the remote from the name-of-the-remote part, and the branch to push to from the name-of-the-branch part. (The branch you are pushing from defaults to your current branch, of course, and it's this current branch's upstream that sets the other two parts.)

Let's say that your current branch is $branch and that its upstream is $remote/$upstream_branch. Using simple or upstream means that:

git push

means:

git push $remote $branch:$upstream_branch

The simple setting adds one extra constraint: this default push will stop (refuse to run) if $upstream_branch is not the same name as $branch.

What current means

Note that both of the above require that the current branch have an upstream. Using current is sort of like using simple, except that Git doesn't require a full upstream setting. It only needs the "remote" part. (You can write git push origin to supply that part, or your current branch can have a remote set, with or without the other half of the upstream.) Instead of needing $upstream_branch, git push now just does:

git push $remote $branch:$branch

Again, the new default is simple and that's usually the right setting.

Answer 2

I would be careful in using git push without specifying the repository and refspec arguments. According to the git-push documentation, git will default to the branch.*.remote repo and the remote.*.push refspec.

In personal practice I always push with something like the following...

git push origin my-branch

You can always use git branch -vv to display what remote each branch is tracking. Would be helpful for further debugging.

Edit: Here is a Stack Overflow answer that looks to be a great explanation on the default behavior of git push