Author here, I started this project over two years ago when one of my friends challenged me to write it. It was based on
https://github.com/sjurba/rebase-editor , but does not require NodeJS/JavaScript. I and several others have been using it almost daily for over a year, so it is ready for general use.
It's written in Rust, but as I only occasionally get a chance to work in the language, development has been slow. I would very much welcome PRs to make improvements and add functionality.