Bug#580939: clean out all the archives except the .debs of installed packages

[jidanni@jidanni.org]

Package: apt
Version: 0.7.25.3
Severity: wishlist

Of the various clean and autoclean commands mentioned on the apt-get and
aptitude man pages, and APT::Clean* options, there is no way to
->clean out all the archives except the .debs of installed packages<-.
E.g., autoclean will also leave uninstalled .debs, if they are in
Packages files.

(There probably is a way: move all the package lists away for a moment
then run autoclean with APT::Clean-Installed=false; But that is a hack.)