Make version passing work.

hosts/common/global/default.nix

@@ -1,3 +1,4 @@
+{ pkgs, self, ... }:
 {
   imports = [
     ./boot.nix
@@ -12,7 +13,7 @@
 
   system.copySystemConfiguration = false; # not supported with flakes
   # Let 'nixos-version --json' know about the Git revision of the flake
-  system.configurationRevision = nixpkgs.lib.mkIf (self ? rev) self.rev;
+  system.configurationRevision = pkgs.lib.mkIf (self ? rev) self.rev;
 
   # This value determines the NixOS release from which the default
   # settings for stateful data, like file locations and database versions