# Rename master to old-master, staging to master
$ (staging) git checkout master
$ (master) git branch -m old-master
$ (old-master) git checkout staging
$ (staging) git branch -m master

# Force push staging (now master) into remote master
$ (master) git push origin master -f

# Change branch names back to original
$ (master) git branch -m staging
$ (staging) git checkout old-master
$ (old-master) git branch -m master

# Sync local master with remote master
$ (master) git fetch --all
$ (master) git reset --hard origin/master