I believe recently Sourceforg added a "Fork"-button to git and mercurial-repositories. Haven't tried it yet, but I think this would allow something similar inside the existing infrastructure
2 clicks for increased privacy: only when you click here the button will be activated and you can send your recommendation to Facebook. The activation will transmit data to third parties – see i.not connected to Facebook
2 clicks for increased privacy: only when you click here the button will be activated and you can send your recommendation to Twitter. The activation will transmit data to third parties – see i.nicht mit Twitter verbunden
2 clicks for increased privacy: only when you click here the button will be activated and you can send your recommendation to Google+. The activation will transmit data to third parties – see i.nicht mit Google+ verbunden