elevation-pr v2.1.0

# first you need a new empty branch; let's call it `newroot`
git checkout --orphan newroot
git rm -rf .

# then you apply the same steps
git commit --allow-empty -m 'root commit'
git rebase --onto newroot --root master
git branch -d newroot

https://stackoverflow.com/questions/645450/insert-a-commit-before-the-root-commit-in-git