version: default Git revision options to `null`

This allows for more uniform handling in the documentation generator,
and avoids lying about the Git reference being `master` internally.

1 files changed, 4 insertions, 3 deletions

diff --git a/modules/system/version.nix b/modules/system/version.nix
index 6801918..0824829 100644
--- a/modules/system/version.nix
+++ b/modules/system/version.nix
@@ -67,8 +67,8 @@ in
 
     system.darwinRevision = mkOption {
       internal = true;
-      type = types.str;
-      default = "master";
+      type = types.nullOr types.str;
+      default = null;
       description = lib.mdDoc "The darwin git revision from which this configuration was built.";
     };
 
@@ -92,7 +92,8 @@ in
 
     system.nixpkgsRevision = mkOption {
       internal = true;
-      type = types.str;
+      type = types.nullOr types.str;
+      default = null;
       description = lib.mdDoc "The nixpkgs git revision from which this configuration was built.";
     };
   };