Installed packages sometimes become obsolete because the package got version bumped and the ebuild for the old version got dropped. Also it happens that packages are dropped completely from the tree (usually for a good reason). I'd like to query those packages in order to take the appropriate action (update, remove).
How to query installed packages that
- have no ebuild for the current installed version; and
- have no ebuild at all anymore (e.g. because it got deleted)