anchor.diff: -{ stdenv, octave, buildEnv
  +{ lib, stdenv, octave, buildEnv
   , makeWrapper, texinfo
   , octavePackages
   , wrapOctave
  
positive.code:       # To point to the new local_list in $out
        addPkgLocalList $out ${octave}
  
        wrapOctavePrograms "${stdenv.lib.concatStringsSep " " packages}"
       '' + postBuild;
  
    inherit (octave) meta;
  
negative.code: 
        createOctavePackagesPath $out ${octave}
  
        for path in ${lib.concatStringsSep " " packages}; do
            if [ -e $path/*.tar.gz ]; then
               $out/bin/octave-cli --eval "pkg local_list $out/.octave_packages; \
                                           pkg prefix $out/${octave.octPkgsPath} $out/${octave.octPkgsPath}; \
  