git repos or similar are practically always derived from the same code base; after all, they're usually merged back in to
But, if you wanted your open source project on GitHub to have a website, you could use GitHub Pages, which lets you publish a site in a repo on a branch named
gh-pages. Unless said open source project is a frontend web app,
gh-pages will by necessity not be based on
Are there any other scenarios where you would want to maintain different branches in the same repo that have completely different code bases or histories?