here is "git commit" in shell: https://git.kernel.org/pub/scm/git/git.git/tree/git-commit-s...

here is "git status", with all its formatting glory: https://git.kernel.org/pub/scm/git/git.git/tree/git-status-s...

but yes, I would not call it "git was written in shell". But some of its significant pieces were.

It's pretty much the only interpretation I can come up with that results in git being written in shell. I do think it's a bit of a stretch though.