anchor.diff:      doCheck = false;
     };
   
  +  enableParallelBuilding = true;
  +
     doCheck = true;
   
     meta = {
  
positive.code: { stdenv, fetchurl, perl, curl, bzip2, sqlite, openssl ? null
  , pkgconfig, boehmgc
  , storeDir ? "/nix/store"
  , stateDir ? "/nix/var"
  }:
  
  stdenv.mkDerivation rec {
    name = "nix-1.0pre26015";
  
    src = fetchurl {
      url = "http://hydra.nixos.org/build/920246/download/4/${name}.tar.bz2";
      sha256 = "d2c9caa8573689de4e95eecaf9829d4b672ea3cb9bdfa825dac0ab0dbffb3c70";
    };
  
    buildNativeInputs = [ perl pkgconfig ];
  
negative.code:     ''
        --with-store-dir=${storeDir} --localstatedir=${stateDir}
        --with-bzip2=${bzip2} --with-sqlite=${sqlite}
        --with-dbi=${perlPackages.DBI}/lib/perl5/site_perl
        --with-dbd-sqlite=${perlPackages.DBDSQLite}/lib/perl5/site_perl
        --disable-init-state
        --enable-gc
        CFLAGS=-O3 CXXFLAGS=-O3
  