Merge pull request #43 from numtide/testing

only set hostPlatform if report.system is present

Author: Mic92

modules/nixos/system.nix

@@ -6,6 +6,6 @@
 }:
 {
   nixpkgs = lib.mkIf (!options.nixpkgs.pkgs.isDefined) {
-    hostPlatform = lib.mkDefault config.facter.report.system;
+    hostPlatform = lib.mkIf (config.facter.report.system or null != null) (lib.mkDefault config.facter.report.system);
   };
 }