Rename master branch for both local and remote Git repositories

The closest thing to renaming is deleting and then recreating on the remote. For example:

git branch -m master master-old
git push remote :master         # Delete master
git push remote master-old      # Create master-old on remote

git checkout -b master some-ref # Create a new local master
git push remote master          # Create master on remote

However, this has a lot of caveats. First, no existing checkouts will know about the rename - Git does not attempt to track branch renames. If the new master doesn't exist yet, git pull will error out. If the new master has been created. the pull will attempt to merge master and master-old. So it's generally a bad idea unless you have the cooperation of everyone who has checked out the repository previously.

Note: Newer versions of Git will not allow you to delete the master branch remotely by default. You can override this by setting the receive.denyDeleteCurrent configuration value to warn or ignore on the remote repository. Otherwise, if you're ready to create a new master right away, skip the git push remote :master step, and pass --force to the git push remote master step. Note that if you're not able to change the remote's configuration, you won't be able to completely delete the master branch!

This caveat only applies to the current branch (usually the master branch); any other branch can be deleted and recreated as above.

Assuming you are currently on master:

git push origin master:master-old        # 1
git branch master-old origin/master-old  # 2
git reset --hard $new_master_commit      # 3
git push -f origin                       # 4

1. First make a master-old branch in the origin repository, based off of the master commit in the local repository.
2. Create a new local branch for this new origin/master-old branch (which will automatically be set up properly as a tracking branch).
3. Now point your local master to whichever commit you want it to point to.
4. Finally, force-change master in the origin repository to reflect your new local master.

(If you do it in any other way, you need at least one more step to ensure that master-old is properly set up to track origin/master-old. None of the other solutions posted at the time of this writing include that.)

git checkout -b new-branch-name
git push remote-name new-branch-name :old-branch-name

You may have to manually switch to new-branch-name before deleting old-branch-name

With Git v1.7, I think this has changed slightly. Updating your local branch's tracking reference to the new remote is now very easy.

git branch -m old_branch new_branch         # Rename branch locally    
git push origin :old_branch                 # Delete the old branch    
git push --set-upstream origin new_branch   # Push the new branch, set local branch to track the new remote