That looks obviously inspired by Quilt, right down to command compatibility like refresh and what not.

Why it's not more popular because:

1. It's impossible to get anyone's attention to anything worthwhile anymore. The modern Internet is structured against it, and there is just too much going on in general.

2. People who are good with Git don't really need it; they can get their commit ducks lined up in a row with interactive rebase. That doesn't have a push/pop discipline, only "waves of push", but it's good enough.

Quilt is still worth knowing about and learning, by the way.