Ensure all systems are using stable repository

Now that we have released Milky Way v0.3, users are strongly advised to use only the stable repository. There may be breaking changes and instability during upcoming developments on White Hole (aka the testing release).

Debug users which are not afraid of a broken system may continue to use this bleeding edge version to report bugs, but it is not to be considered stable for daily use.

We are currently working on the following tasks: