! [rejected] master -> master (non-fast-forward) on a new up-to-date branch

Question

In my repo, I have a master branch, and a new branch.

I've been working on new for a while, making commits, and pushes as I go. I decided now to branch off new and call it newest. So I did

git checkout -b "newest"

and the branch was successfully created. I added a file, and started working on it. I committed my changes a couple of times.

BUT when I try to push this new branch and my changes to it to origin, I get this error:

C:\wamp\www\myproj>git push origin
To https://github.com/Imray/Proj.git
 ! [rejected]        master -> master (non-fast-forward)
 ! [rejected]        new -> new (non-fast-forward)
error: failed to push some refs to 'https://github.com/Imray/Proj.git'
hint: Updates were rejected because a pushed branch tip is behind its remote
hint: counterpart. Check out this branch and integrate the remote changes
hint: (e.g. 'git pull ...') before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details. 

So, as specified in the instructions, I tried git pull, but then I got:

There is no tracking information for the current branch.
Please specify which branch you want to merge with.
See git-pull(1) for details

    git pull <remote> <branch>

If you wish to set tracking information for this branch you can do so with:

    git branch --set-upstream-to=origin/<branch> newest

I'm stuck.

How do I push my new branch and the changes to github?

Solution

Check your git config push.default. It might be on "matching", since it tries to push all existing branches.
That was the default before Git 2.0+.

I would recommend setting it to "simple", in order to push only the current branch.

That being said, to push a branch, you need (for the first push) to setup an upstream branch.

For a branch never pushed before:

git push -u origin newest

For a branch which does exists on the upstream repo:

git branch --set-upstream-to=origin/master master
git branch --set-upstream-to=origin/new new

Then a git checkout master ; git pull would work.