I'm not sure if it's just me, but
git push -u origin some-new-branch does not work for me, trying to push commits will result in a 403 error. Apparently 'origin' is set to the same as upstream by default, in this case it's CleverRaven/Cataclysm-DDA.git . I had to change it to my own repo using
git remote set-url origin https://github.com/infectedmochi/Cataclysm-DDA.git And it works fine again.
Edit: And I can't replicate this :/ Maybe it was a screw-up on my part after all.