anchor.diff:  
     src = fetchgit {
       url = https://github.com/rust-lang/rust;
  -    rev = "63666317214788329e0b7680929b09823f127d83";
  -    sha256 = "1saf6ycy5dzp1bxypzqisi4g4p0y1czbgr82xbrw5c81x5c274zk";
  +    rev = "6539cb417f4a7c2d9d1afce44c196578d2b67f38";
  +    sha256 = "14nc42j46hvlqms77245vil2wplmvci3ramxrmjyjqg0bql1w28m";
     };
   
     # We need rust to build rust. If we don't provide it, configure will try to download it.
  
positive.code: 
  */
  
  with ((import ./common.nix) {inherit stdenv; version = "0.13.0-pre-2763-g6366631";});
  
  let snapshot = if stdenv.system == "i686-linux"
        then "3daf531aed03f5769402f2fef852377e2838db98"
        else if stdenv.system == "x86_64-linux"
        then "4f3c8b092dd4fe159d6f25a217cf62e0e899b365"
        else if stdenv.system == "i686-darwin"
        then "2a3e647b9c400505bd49cfe56091e866c83574ca"
        else if stdenv.system == "x86_64-darwin"
        then "5e730efc34d79a33f464a87686c10eace0760a2e"
        else abort "no-snapshot for platform ${stdenv.system}";
      snapshotDate = "2014-12-20";
      snapshotRev = "8443b09";
      snapshotName = "rust-stage0-${snapshotDate}-${snapshotRev}-${platform}-${snapshot}.tar.bz2";
  
  in stdenv.mkDerivation {
  
negative.code: 
      substituteInPlace src/rust-installer/gen-install-script.sh \
        --replace /bin/echo "${coreutils}/bin/echo"
      substituteInPlace src/rust-installer/gen-installer.sh \
        --replace /bin/echo "${coreutils}/bin/echo"
    '';
  
    buildInputs = [ which file perl curl python27 makeWrapper git valgrind procps ];
  