restore the defaults entry in the network file

data/eval-machines.nix

@@ -13,13 +13,17 @@ let
 in with lib;
 
 let
+  defaults = network.defaults or {};
+
   modules = { machineName, nodes, check }:
     [
       # Get the configuration of this machine from each network
       # expression, attaching _file attributes so the NixOS module
       # system can give sensible error messages.
       { imports = [ network.${machineName} ]; }
 
+      defaults
+
       ({ lib, ... }: {
         key = "deploy-stuff";
         imports = [ ./options.nix ];