This repository is discontinued due to new restrictive laws regulating the Internet in Russia. In some cases they place responsibility on the "proprietor of the software". Which open-source software does not have. So the story will go something like this.
In light of the above maintaining this repository is no longer worth the risk for me.
You can still install cjdns from source, which is pretty easy. See https://github.com/cjdelisle/cjdns/ for official installation instructions.