anchor.diff:        perlDeps perl nix
         postgresql # for running the tests
         nlohmann_json
  -    ] ++ lib.optionals isGreaterNix20 [ boost ];
  +      boost
  +    ];
   
     hydraPath = lib.makeBinPath (
       [ sqlite subversion openssh nix coreutils findutils pixz
  
positive.code: 
    nativeBuildInputs = [ autoreconfHook pkgconfig ];
  
    # adds a patch which ensures compatibility with the API of Nix 2.0.
    # it has been reverted in https://github.com/NixOS/hydra/commit/162d671c48a418bd10a8a171ca36787ef3695a44,
    # for Nix 2.1/unstable compatibility. Reapplying helps if Nix 2.0 is used to keep the build functional.
    patches = lib.optionals (!isGreaterNix20) [
      (fetchpatch {
        url = "https://github.com/NixOS/hydra/commit/08de434bdd0b0a22abc2081be6064a6c846d3920.patch";
        sha256 = "0kz77njp5ynn9l81g3q8zrryvnsr06nk3iw0a60187wxqzf5fmf8";
      })
    ] ++ [
      (fetchpatch {
        url = "https://github.com/NixOS/hydra/pull/648/commits/4171ab4c4fd576c516dc03ba64d1c7945f769af0.patch";
        sha256 = "1fxa2459kdws6qc419dv4084c1ssmys7kqg4ic7n643kybamsgrx";
  
negative.code: else
  
  let
    perlDeps = buildEnv {
      name = "hydra-perl-deps";
      paths = with perlPackages;
  