darwin.builder: Fix gratuitous rebuilds

See the discussion starting here:

https://github.com/NixOS/nixpkgs/pull/206951#issuecomment-1364760917

The `darwin.builder` derivation had a gratuitous dependency
on the current Nixpkgs revision due to
`config.system.nixos.revision`.  Setting the revision explicitly
to null fixes this problem and prevents the derivation from being
rebuilt on every change to Nixpkgs.

1 files changed, 6 insertions, 1 deletions

diff --git a/nixos/modules/profiles/macos-builder.nix b/nixos/modules/profiles/macos-builder.nix
index 0cbac3bd61fed..15fad007bd3ed 100644
--- a/nixos/modules/profiles/macos-builder.nix
+++ b/nixos/modules/profiles/macos-builder.nix
@@ -93,7 +93,12 @@ in
         };
       });
 
-  system.stateVersion = "22.05";
+  system = {
+    # To prevent gratuitous rebuilds on each change to Nixpkgs
+    nixos.revision = null;
+
+    stateVersion = "22.05";
+  };
 
   users.users."${user}"= {
     isNormalUser = true;