anchor.diff:    });
   
     nixUnstable = lib.lowPrio (callPackage common rec {
  -    name = "nix-3.0${suffix}";
  -    suffix = "pre20201020_e0ca98c";
  +    name = "nix-2.4${suffix}";
  +    suffix = "pre20201102_550e11f";
   
       src = fetchFromGitHub {
         owner = "NixOS";
         repo = "nix";
  -      rev = "e0ca98c2071b815578470e280df8fdb750c7e23b";
  -      hash = "sha256-KVS/Z6FzMBOl5XCyOLwfiVoX7G2LQRa9HMGNnJRPCoo=";
  +      rev = "550e11f077ae508abde5a33998a9d4029880e7b2";
  +      sha256 = "186grfxsfqg7r92wgwbma66xc7p3iywn43ff7s59m4g6bvb0qgcl";
       };
   
       inherit storeDir stateDir confDir boehmgc;
  
positive.code:             patchelf --set-rpath $out/lib:${stdenv.cc.cc.lib}/lib $out/lib/libboost_thread.so.*
            ''}
          '' +
          # For Nix 3.0, patch around an issue where the Nix configure step pulls in the
          # build system's bash and other utilities when cross-compiling
          lib.optionalString (stdenv.buildPlatform != stdenv.hostPlatform && isExactly30) ''
            mkdir tmp/
            substitute corepkgs/config.nix.in tmp/config.nix.in \
              --subst-var-by bash ${bash}/bin/bash \
  
negative.code:       inherit name src;
        version = lib.getVersion name;
  
        is24 = lib.versionAtLeast version "2.4pre";
        isExactly24 = lib.versionAtLeast version "2.4" && lib.versionOlder version "2.4";
  
        VERSION_SUFFIX = suffix;
  
  