I have 2 git branches: master and experimental.
Experimental became good, I want to make it the master. I figured I would rename to shuffle things around, but here is what I got:
nutebook:Stuff nathan$ git remote rename master old
error: Could not rename config section 'remote.master' to 'remote.old'
I use GitHub and Git-Tower.
The following is a guide to rename your master branch. It will work just as easily to rename your experimental branch.
see this site.