Comment 54 for bug 125103

Martin, unfortunately users are always suggested to uncheck any third-party repositories before upgrading to a new release. Anything that doesn't belong to the original distribution can and probably will create problems.
But I agree that it is an issue that must be solved somehow - perhaps explaining that the users should remove/disable any third-party software repositories?

My opinion is that unsigned packages (or unsigned packages list) shouldn't be allowed to be installed, as it is a common security risk that I believe none of us wishes to take.