XScreenSaver's author opens a GitHub repo just to say there isn't one
There is no official XScreenSaver GitHub repository
Jamie Zawinski, the author of XScreenSaver, created a GitHub repository whose only purpose is to declare that no official XScreenSaver repository exists. He publishes releases as tar files on his own website and nowhere else, and warns that any other XScreenSaver repo on GitHub or elsewhere has nothing to do with him and shouldn't be trusted. Change requests are welcome by email. The repo has already drawn over 1,000 stars.
If you see any other XScreenSaver repository (on GitHub or elsewhere) that has nothing to do with me and you should not trust it.