It's a joke, that is based on the monad joke, but without actually getting the monad joke.
The monad joke is funny on three levels:
- it tries to explain abstract mathematical jargon with even more mathematical jargon, which is even more abstract
- however, the explanation is actually correct
- and once you dive deeper into category theory, you will actually start to see monads as "just a monoid in the category of endofunctors"
The Git thing, however, is just random gibberish. It is meant to resemble the monad joke, and might also be a jab at the darcs patch theory, but fundamentally, the person making the joke didn't understand the monad joke.
This is the original tweet containing the quote:
Wil Shipley (@wilshipley): Sweet god I hate git.
Isaac Wolkerstorfer (@agnoster): @wilshipley git gets easier once you get the basic idea that branches are homeomorphic endofunctors mapping submanifolds of a Hilbert space.
And this is a comment on Quora by the original author of the tweet:
To confirm what Leo said, it was intended as a joke. […]
It was intended as firmly tongue-in-cheek. I actually love git, and I think its complexity is greatly overblown. At the same time, I'm sympathetic to the fact that advice from git gurus to novices can end up sounding like inscrutable gibberish.
It's not intended to have any deeper meaning. […]
The Leo he is referring to is another answerer in the same thread, a mathematician, who basically explains why that is nonsense. (Hilbert spaces are continuous, patches and branches are discrete.)
He also explains that he was inspired by this blog post (A Guide to GIT using spatial analogies), which actually does make sense.