https://github.com/null https://github.com/null is a user. I'm not sure I understand your comment. I could not find github's username blacklist, so I don't thi

https://github.com/null https://github.com/null is a user. I'm not sure I understand your comment. I could not find github's username blacklist, so I don't think it's "transparently obvious", but if there is a blacklist feel free to share it.