flake: refactor to differentiate common modules

flake.nix

@@ -9,19 +9,17 @@
 
   outputs = { self, nixpkgs, nur, home-manager }:
     let
-      buildHost = name: system: nixpkgs.lib.nixosSystem {
-        inherit system;
-        modules = [
+      inherit (nixpkgs) lib;
+
+      defaultModules = [
         ({ pkgs, ... }: {
           # Let 'nixos-version --json' know about the Git revision
-            # of this flake.
           system.configurationRevision =
             if self ? rev
             then self.rev
             else throw "Refusing to build from a dirty Git tree!";
         })
         { nixpkgs.overlays = [ nur.overlay ]; }
-          (./. + "/${name}.nix")
         home-manager.nixosModules.home-manager
         {
           home-manager.users.ambroisie = import ./home;
@@ -30,6 +28,12 @@
           home-manager.useUserPackages = true;
         }
       ];
+
+      buildHost = name: system: lib.nixosSystem {
+        inherit system;
+        modules = defaultModules ++ [
+          (./. + "/${name}.nix")
+        ];
       };
     in
     {