GitHub is closed in the sense that you can't access most of its source code but it's not really a problem since Git is decentralised. When you clone a repository from GitHub, you have everything you need to host that repository somewhere else. GitHub doesn't take any power away from the project - it only provides tools to easily manage your project.
I'm not sure that status of downloading a project's issues or wiki but I remember they were working on making them clonable.
I'm not sure that status of downloading a project's issues or wiki but I remember they were working on making them clonable.