anchor.diff:    /* The set of supported Dpkg-based distributions. */
   
     debDistros = {
  -
  -    # Interestingly, the SHA-256 hashes provided by Ubuntu in
  -    # http://nl.archive.ubuntu.com/ubuntu/dists/{gutsy,hardy}/Release are
  -    # wrong, but the SHA-1 and MD5 hashes are correct.  Intrepid is fine.
  -
  -    ubuntu1204i386 = {
  -      name = "ubuntu-12.04-precise-i386";
  -      fullName = "Ubuntu 12.04 Precise (i386)";
  -      packagesLists =
  -        [ (fetchurl {
  -            url = "mirror://ubuntu/dists/precise/main/binary-i386/Packages.bz2";
  -            sha256 = "18ns9h4qhvjfcip9z55grzi371racxavgqkp6b5kfkdq2wwwax2d";
  -          })
  -          (fetchurl {
  -            url = "mirror://ubuntu/dists/precise/universe/binary-i386/Packages.bz2";
  -            sha256 = "085lkzbnzkc74kfdmwdc32sfqyfz8dr0rbiifk8kx9jih3xjw2jk";
  -          })
  -        ];
  -      urlPrefix = "mirror://ubuntu";
  -      packages = commonDebPackages ++ [ "diffutils" ];
  -    };
  -
  -    ubuntu1204x86_64 = {
  -      name = "ubuntu-12.04-precise-amd64";
  -      fullName = "Ubuntu 12.04 Precise (amd64)";
  -      packagesLists =
  -        [ (fetchurl {
  -            url = "mirror://ubuntu/dists/precise/main/binary-amd64/Packages.bz2";
  -            sha256 = "1aabpn0hdih6cbabyn87yvhccqj44q9k03mqmjsb920iqlckl3fc";
  -          })
  -          (fetchurl {
  -            url = "mirror://ubuntu/dists/precise/universe/binary-amd64/Packages.bz2";
  -            sha256 = "0x4hz5aplximgb7gnpvrhkw8m7a40s80rkm5b8hil0afblwlg4vr";
  -          })
  -        ];
  -      urlPrefix = "mirror://ubuntu";
  -      packages = commonDebPackages ++ [ "diffutils" ];
  -    };
  -
       ubuntu1404i386 = {
         name = "ubuntu-14.04-trusty-i386";
         fullName = "Ubuntu 14.04 Trusty (i386)";
  
positive.code:           (fetchurl {
              url = "mirror://ubuntu/dists/bionic/universe/binary-amd64/Packages.xz";
              sha256 = "1832nqpn4ap95b3sj870xqayrza9in4kih9jkmjax27pq6x15v1r";
            })
          ];
        urlPrefix = "mirror://ubuntu";
  
negative.code:       packages = commonDebPackages ++ [ "diffutils" "libc-bin" ];
      };
  
      ubuntu1804i386 = {
        name = "ubuntu-18.04-bionic-i386";
        fullName = "Ubuntu 18.04 Bionic (i386)";
  