anchor.diff:  
     nativeBuildInputs = [ autoreconfHook ];
   
  -  buildInputs = [ unzip libjpeg libtiff libpng proj openssl sqlite
  -    libspatialite libgeotiff poppler hdf4 qhull giflib expat libxml2 ]
  -  ++ (with pythonPackages; [ python numpy wrapPython ])
  -  ++ stdenv.lib.optional stdenv.isDarwin libiconv
  -  ++ stdenv.lib.optionals netcdfSupport [ netcdf hdf5 curl ];
  +  buildInputs = [
  +    unzip
  +    libjpeg
  +    libtiff
  +    libpng
  +    proj
  +    openssl
  +    sqlite
  +    libspatialite
  +    libgeotiff
  +    poppler
  +    hdf4
  +    qhull
  +    giflib
  +    expat
  +    libxml2
  +  ] ++ (with pythonPackages; [ python numpy wrapPython ])
  +    ++ stdenv.lib.optional stdenv.isDarwin libiconv
  +    ++ stdenv.lib.optionals netcdfSupport [ netcdf hdf5 curl ];
   
     configureFlags = [
       "--with-expat=${expat.dev}"
       "--with-jpeg=${libjpeg.dev}"
       "--with-libtiff=${libtiff.dev}" # optional (without largetiff support)
  -    "--with-png=${libpng.dev}"      # optional
  +    "--with-png=${libpng.dev}" # optional
       "--with-poppler=${poppler.dev}" # optional
  -    "--with-libz=${zlib.dev}"       # optional
  +    "--with-libz=${zlib.dev}" # optional
       "--with-pg=${postgresql}/bin/pg_config"
       "--with-mysql=${libmysqlclient}/bin/mysql_config"
       "--with-geotiff=${libgeotiff}"
       "--with-sqlite3=${sqlite.dev}"
       "--with-spatialite=${libspatialite}"
  -    "--with-python"               # optional
  +    "--with-python" # optional
       "--with-proj=${proj.dev}" # optional
  -    "--with-geos=${geos}/bin/geos-config"# optional
  +    "--with-geos=${geos}/bin/geos-config" # optional
       "--with-hdf4=${hdf4.dev}" # optional
       "--with-xml2=${libxml2.dev}/bin/xml2-config" # optional
       (if netcdfSupport then "--with-netcdf=${netcdf}" else "")
  
positive.code: { stdenv, fetchFromGitHub, fetchpatch, unzip, libjpeg, libtiff, zlib
  , postgresql, libmysqlclient, libgeotiff, pythonPackages, proj, geos, openssl
  , libpng, sqlite, libspatialite, poppler, hdf4, qhull, giflib, expat
  , libiconv, libxml2, autoreconfHook
  , netcdfSupport ? true, netcdf, hdf5, curl
  }:
  
  with stdenv.lib;
  
  
negative.code:   # - Unset CC and CXX as they confuse libtool.
    # - teach gdal that libdf is the legacy name for libhdf
    preConfigure = ''
      substituteInPlace configure \
      --replace "-lmfhdf -ldf" "-lmfhdf -lhdf"
    '';
  
    preBuild = ''
      substituteInPlace swig/python/GNUmakefile \
  