anchor.diff:  
           echo "${pkgs.stdenv.buildPlatform.system}" > $out/nix-support/system
           if test -n "$compressImage"; then
  -          echo "file sd-image $img.bz2" >> $out/nix-support/hydra-build-products
  +          echo "file sd-image $img.zst" >> $out/nix-support/hydra-build-products
           else
             echo "file sd-image $img" >> $out/nix-support/hydra-build-products
           fi
  
positive.code:         fsck.vfat -vn firmware_part.img
          dd conv=notrunc if=firmware_part.img of=$img seek=$START count=$SECTORS
          if test -n "$compressImage"; then
              bzip2 $img
          fi
        '';
      }) {};
  
negative.code:       default = true;
        description = ''
          Whether the SD image should be compressed using
          <command>zstd</command>.
        '';
      };
  
  