anchor.diff:  }:
   
   let
  -  version = "2019-02-13";
  +  date = "2019-02-13";
   in
   stdenv.mkDerivation rec {
  -  name = "egl-headers-${version}";
  +  name = "egl-headers-${date}";
   
     src = fetchurl {
       url = "http://egl-registry.tar.xz";
  -    multihash = "Qmf3CaunyCXXiyyd6fypvYZv6Q8cDU28ZnJkLqauH26Wxn";
  -    sha256 = "263cd3090ab76adc3fba3e8e97ba54b44e1109c8e15dfca99851c255319b0f9b";
  +    multihash = "Qma9rtynxUNEy8AxSsuEE7kCNqYvMU8bTeJQL8CiYo27TU";
  +    sha256 = "de926279c49b99d2d702217a073cf25b60d58cb81a30a91150cc0892b2b32532";
     };
   
     configurePhase = ":";
  
positive.code: 
    passthru = {
      generateDistTarball = stdenv.mkDerivation rec {
        name = "egl-headers-dist-${version}";
  
        src = fetchFromGitHub {
          version = 6;
  
negative.code:         patchShebangs api/genheaders.py
          patchShebangs api/reg.py
  
          # Remove generated headers stored in the repo
          rm -v api/EGL/egl{,ext}.h
  
          # Fix impure date in headers
          grep -q "time.strftime('%Y%m%d')" api/genheaders.py
          sed -i api/genheaders.py \
            -e "s,time.strftime('%Y%m%d'),'${lib.replaceStrings ["-"] [""] date}',"
        '';
  
        configurePhase = ":";
  