anchor.diff:          comm <(sort -n baseFiles|uniq) \
                <(sort -n layerFiles|uniq|grep -v ${layer}) -1 -3 > newFiles
           # Append the new files to the layer.
  -        tar -rpf temp/layer.tar --mtime=0 --no-recursion --files-from newFiles
  +        tar -rpf temp/layer.tar --mtime="@$SOURCE_DATE_EPOCH" \
  +          --owner=0 --group=0 --no-recursion --files-from newFiles
   
           echo "Adding meta..."
   
  
positive.code: 
          echo "Packing layer..."
          mkdir $out
          tar -C layer --mtime=0 -cf $out/layer.tar .
  
          # Compute the tar checksum and add it to the output json.
          echo "Computing checksum..."
  
negative.code:         echo "Adding contents..."
          for item in ${toString contents}; do
            echo "Adding $item..."
            rsync -ak --chown=0:0 $item/ layer/
          done
        '';
  
  