anchor.diff:  
     src =  fetchurl {
       urls = [
  +      "https://mesa.freedesktop.org/archive/mesa-${version}.tar.xz"
         "https://mesa.freedesktop.org/archive/${version}/mesa-${version}.tar.xz"
         "ftp://ftp.freedesktop.org/pub/mesa/${version}/mesa-${version}.tar.xz"
         # Tarballs for old releases are moved to another directory
  
positive.code:     optionalString
      splitString;
  
    version = "17.0.0";
  
    # this is the default search path for DRI drivers
    driverSearchPath = "/run/opengl-driver-${stdenv.targetSystem}";
  
negative.code:         + head (splitString "." version)
          + ".x/${version}/mesa-${version}.tar.xz")
      ];
      multihash = "QmTZJ4bQcVnHMqGs6Q8jqwB4ZbasYWRfo7oa3CHKfnAew6";
      hashOutput = false;  # Provided by upstream directly
      sha256 = "96fd70ef5f31d276a17e424e7e1bb79447ccbbe822b56844213ef932e7ad1b0c";
    };
  
    nativeBuildInputs = [
  