git: Set master to old commit

back-to-old-commit.sh

git checkout master~1            # Checkout previous commit on master
git checkout -b new_master       # Create branch for new master
git branch -D master             # Delete old master
git branch -mv new_master master # Make new_master master
 
# source: http://stackoverflow.com/questions/4359681/want-to-change-my-master-to-an-older-commit-how-can-i-do-this