Build using the nix flake

release.nix

@@ -2,14 +2,14 @@
 , nixpkgs ? builtins.fetchGit { url = https://github.com/NixOS/nixpkgs-channels.git; ref = "nixos-19.03-small"; }
 , officialRelease ? false
 , shell ? false
+, pkgs ? import nixpkgs { system = "x86_64-linux"; }
+, nix ? pkgs.nixUnstable or pkgs.nix
 }:
 
-with import (nixpkgs + "/lib");
+with pkgs.lib;
 
 let
 
-  pkgs = import nixpkgs { system = "x86_64-linux"; };
-
   genAttrs' = genAttrs [ "x86_64-linux" /* "i686-linux" */ ];
 
   hydraServer = hydraPkg:
@@ -44,8 +44,6 @@ rec {
 
     let
 
-      nix = pkgs.nixUnstable or pkgs.nix;
-
       perlDeps = buildEnv {
         name = "hydra-perl-deps";
         paths = with perlPackages;