anchor.diff:    # the bootstrap.  In all stages, we build an stdenv and the package
     # set that can be built with that stdenv.
     stageFun =
  -    {gccPlain, glibc, binutils, coreutils, name, overrides ? (pkgs: {}), extraBuildInputs ? []}:
  +    {gccPlain, glibc, binutils, coreutils, gnugrep, name, overrides ? (pkgs: {}), extraBuildInputs ? []}:
   
       let
   
  
positive.code:         isGNU = true;
          cc = stage4.stdenv.cc.cc;
          libc = stage4.pkgs.glibc;
          inherit (stage4.pkgs) binutils coreutils;
          name = "";
          stdenv = stage4.stdenv;
          shell = stage4.pkgs.bash + "/bin/bash";
  
negative.code:     glibc = null;
      binutils = null;
      coreutils = null;
      gnugrep = null;
      name = null;
  
      overrides = pkgs: {
  