anchor.diff:      owner  = "tvheadend";
       repo   = "tvheadend";
       rev    = "v${version}";
  -    sha256 = "1lhk8psvifmn4kjwyfxjj21z0apyr59zizzsfd4j22v7bk66rrl9";
  +    sha256 = "1kydjmgv0nrllgi2s6aczq4x9ag01c8qm8w962qb52fzdfw7fs6k";
     };
   
     buildInputs = [
  
positive.code: , which, zlib }:
  
  let
    version = "4.2.1";
  
  in stdenv.mkDerivation rec {
    name = "tvheadend-${version}";
  
negative.code:   preConfigure = ''
      patchShebangs ./configure
  
      substituteInPlace src/config.c \
        --replace /usr/bin/tar ${gnutar}/bin/tar
  
      # the version detection script `support/version` reads this file if it
      # exists, so let's just use that
  