anchor.diff:  { stdenv, fetchurl, composableDerivation, unzip, libjpeg, libtiff, zlib
  -, postgresql, mysql, libgeotiff, python, pythonPackages, proj, geos, openssl }:
  +, postgresql, mysql, libgeotiff, python, pythonPackages, proj, geos, openssl
  +, libpng }:
   
   composableDerivation.composableDerivation {} (fixed: rec {
     version = "1.11.2";
  
positive.code:     sha256 = "66bc8192d24e314a66ed69285186d46e6999beb44fc97eeb9c76d82a117c0845";
    };
  
    buildInputs = [ unzip libjpeg libtiff python pythonPackages.numpy proj openssl ];
  
    # Don't use optimization for gcc >= 4.3. That's said to be causing segfaults.
    # Unset CC and CXX as they confuse libtool.
  
negative.code:   configureFlags = [
      "--with-jpeg=${libjpeg}"
      "--with-libtiff=${libtiff}" # optional (without largetiff support)
      "--with-libpng=${libpng}"   # optional
      "--with-libz=${zlib}"       # optional
  
      "--with-pg=${postgresql}/bin/pg_config"
  