nixos/gnome3: don't enable modules for excludePackages

nixos/modules/services/x11/desktop-managers/gnome3.nix

@@ -363,15 +363,6 @@ in
         /* gnome-boxes */
       ] config.environment.gnome3.excludePackages);
 
-      # Enable default programs
-      programs.evince.enable = mkDefault true;
-      programs.file-roller.enable = mkDefault true;
-      programs.geary.enable = mkDefault true;
-      programs.gnome-disks.enable = mkDefault true;
-      programs.gnome-terminal.enable = mkDefault true;
-      programs.seahorse.enable = mkDefault true;
-      services.gnome3.sushi.enable = mkDefault true;
-
       # Let nautilus find extensions
       # TODO: Create nautilus-with-extensions package
       environment.sessionVariables.NAUTILUS_EXTENSION_DIR = "${config.system.path}/lib/nautilus/extensions-3.0";
@@ -384,6 +375,25 @@ in
       ];
     })
 
+    # Enable default program modules
+    # Since some of these have a corresponding package, we only
+    # enable that program module if the package hasn't been excluded
+    # through `environment.gnome3.excludePackages`
+    (
+    let
+      notExcluded = pkg: mkDefault (!(lib.elem pkg config.environment.gnome3.excludePackages));
+    in
+    with pkgs.gnome3;
+    {
+      programs.evince.enable = notExcluded evince;
+      programs.file-roller.enable = notExcluded file-roller;
+      programs.geary.enable = notExcluded geary;
+      programs.gnome-disks.enable = notExcluded gnome-disk-utility;
+      programs.gnome-terminal.enable = notExcluded gnome-terminal;
+      programs.seahorse.enable = notExcluded seahorse;
+      services.gnome3.sushi.enable = notExcluded sushi;
+    })
+
     (mkIf serviceCfg.games.enable {
       environment.systemPackages = (with pkgs.gnome3; removePackagesByName [
         aisleriot atomix five-or-more four-in-a-row gnome-chess gnome-klotski