anchor.diff:  
     src = fetchurl {
       url = "mirror://gnu/gdb/${basename}.tar.bz2";
  -    sha256 = "0ljkv3xkpqg4x38mrmzx4b7h1bkpfy41vmi5q8nnakhajzbjfb0l";
  +    sha256 = "1w0h6hya0bl46xddd57mdzwmffplwglhnh9x9hv46ll4mf44ni5z";
     };
   
     # TODO: Add optional support for Python scripting.
  -  buildInputs = [ ncurses readline gmp mpfr expat texinfo ];
  +  buildInputs = [ ncurses readline gmp mpfr expat texinfo ]
  +    ++ stdenv.lib.optional doCheck dejagnu;
   
     configureFlags =
       '' --with-gmp=${gmp} --with-mpfr=${mpfr} --with-system-readline
  
positive.code: { fetchurl, stdenv, ncurses, readline, gmp, mpfr, expat, texinfo
  , target ? null }:
  
  let
      basename = "gdb-7.1";
  in
  stdenv.mkDerivation rec {
    name = basename + stdenv.lib.optionalString (target != null)
  
negative.code:     '' # Remove Info files already provided by Binutils and other packages.
         rm -v $out/share/info/{standards,configure,bfd}.info
      '';
  
    # TODO: Investigate & fix the test failures.
    doCheck = false;
  
    meta = {
      description = "GDB, the GNU Project debugger";
  