linus messed up the linux git history (so now there's a new git option)

Git repositories can have multiple root commits, which can cause problems with history traversal, file tracking, and bisection. This became a notable issue when Linus Torvalds accidentally merged an unrelated GitHub-generated README into the Linux kernel, creating a second root commit. The incident led to Git introducing the `--allow-unrelated-histories` flag, which now prevents accidental merges of unrelated histories by default. You can find root commits using `git log --max-parents=0` and should be cautious when merging pull requests that might introduce new roots.