anchor.diff:  let
     configParser = ''
       function parseconfig {
  -        set -x
           while read LINE; do
               NAME=`echo "$LINE" | cut -d \  -f 1`
               OPTION=`echo "$LINE" | cut -d \  -f 2`
  
positive.code:             fi
  
              echo "parseconfig: removing $NAME"
              sed -i /^$NAME=/d .config
  
              echo "parseconfig: setting $NAME=$OPTION"
              echo "$NAME=$OPTION" >> .config
          done
          set +x
      }
    '';
  
  
negative.code: in
  
  stdenv.mkDerivation rec {
    name = "busybox-1.19.4";
  
    src = fetchurl {
      url = "http://busybox.net/downloads/${name}.tar.bz2";
      sha256 = "1vhh6xa71w4wzby0f4x357fv6zxvkklmyjc8njgbbzv1v83391cv";
    };
  
    configurePhase = ''
  