anchor.diff:          echo "Adding contents..."
           for item in ${toString contents}; do
             echo "Adding $item..."
  -          rsync -ak --chown=0:0 $item/ layer/
  +          rsync -a${if keepContentsDirlinks then "K" else "k"} --chown=0:0 $item/ layer/
           done
         '';
   
  
positive.code:     fromImageTag ? null,
      # Files to put on the image (a nix store path or list of paths).
      contents ? null,
      # Docker config; e.g. what command to run on the container.
      config ? null,
      # Optional bash script to run on the files prior to fixturizing the layer.
  
negative.code:         if runAsRoot == null
          then mkPureLayer {
            name = baseName;
            inherit baseJson contents keepContentsDirlinks extraCommands;
          } else mkRootLayer {
            name = baseName;
            inherit baseJson fromImage fromImageName fromImageTag
                    contents keepContentsDirlinks runAsRoot diskSize
                    extraCommands;
          };
        result = runCommand "docker-image-${baseName}.tar.gz" {
          buildInputs = [ jshon pigz coreutils findutils ];
  