we have this:

    package = (pkgs.hydra-unstable.overrideAttrs (oA: rec {
      name = "${oA.pname}-${version}";
      version = "unstable-2022-03-10";

      src = pkgs.fetchFromGitHub {
        owner = "nixos";
        repo = "hydra";
        rev = "b67608964c1dae26f7b31925fd2f32c76d8c6ca6";
        sha256 = "sha256-ASORHIoPAf/SsHZUmuvvp1i15J8oPluUCMe8jozJdss=";
      };

      patches = let
        prPatches = [
          # Kill buttons
          { id = "836"; sha256 = "sha256-A0Hl4n3B7PQFtJhS1wBGYLjoabiT059TBNU3+lD5nIw="; }
          # GitInput: Avoid fetch if rev is available
          { id = "868"; sha256 = "sha256-dTFGWhfiANs5Z5ScmZxFaCZPZfAVBJOceEOvVMHShSw="; }
          # queue-runner status in topbar
          { id = "869"; sha256 = "sha256-iFpMV4Z5VE7YmvnAHAydUQYk0FNKNarPYqRHEAuT4/w="; }
          # tailon
          { id = "957"; sha256 = "sha256-1XZpDVf1OXLptWIIMhZjO2QVNoE95pPhLC/7bparZF0="; }
          # Make eval restriction an option instead of forcing
          { id = "888"; sha256 = "sha256-TCJEmTkycUWTx7U433jaGzKwpbCyNdXqiv9UfhsHnfs="; }
          # improved UI
          { id = "965"; sha256 = "sha256-bOtHGYa1r4CUZVRyRET6C/qRp4L4lKSbezbtVqfVA8o="; }
          # Dynamic RunCommand
          # Does not apply
          #{ id = "1103"; sha256 = "sha256-AaWdKiFuxNscw9TwPQAeQG/xcFb4YN1EFVqRLu00S5w="; }
          # Fix local store detection and related issues
          { id = "1156"; sha256 = "sha256-uSCmJ8AESSFLcCrcPA2AS9UFo+w5mhZB7zFqb1k/sJA="; }
          # jobsets: Show status of next evaluation as emoji
          { id = "1157"; sha256 = "sha256-VtpKSLh/Xy31lJUnlONK8rt370sIzMm7fjxCWKvQdiY="; }
          # Make the use of substitutes on builders configurable
          { id = "1158"; sha256 = "sha256-K9FUlJZ5VTAwJYzmCaHuj+R4AYk4HDH510sRQ2LMfUw="; }
        ];
      in oA.patches ++ map (p: pkgs.fetchpatch {
        url = "https://patch-diff.githubusercontent.com/raw/NixOS/hydra/pull/${p.id}.patch";
        inherit (p) sha256;
        includes = [
          "src/**"
          "*.am"
          "*.ac"
          "bootstrap"
        ];
      }) prPatches;

      buildInputs = oA.buildInputs ++ (with pkgs.perlPackages; [
        CatalystAuthenticationStoreLDAP
        CatalystPluginPrometheusTiny
        FileSlurper
        IPCRun3
        LinuxInotify2
        ListSomeUtils
        ParallelForkManager
        ReadonlyX
        UUID4Tiny
      ]);

      doCheck = false;

      # Insert the correct version into the wrapper
      postInstall = ''
        ${oA.postInstall}
        sed -i 's/^.*HYDRA_RELEASE.*$/export HYDRA_RELEASE="${removePrefix "unstable-" version}"/g' $out/bin/hydra-server
      '';

    })).override {
      nix = config.nix.package;
    };