Get rid of obsolete prints on non-flakes example.

[vic]

Setting system.stateVersion does remove the warning, but has no effect on the obsolete prints.

I tried defining a new nixos machine using nixpkgs.lib.nixosSystem directly, and that does not produce those obsolete prints:

default.nix

let

  outputs =
    inputs:
     inputs.nixpkgs.lib.recursiveUpdate (inputs.nixpkgs.lib.evalModules {
      modules = [ (inputs.import-tree ./modules) ];
      specialArgs = {
        inherit inputs;
        inherit (inputs) self;
      };
    }).config {
      flake.nixosConfigurations.works = inputs.nixpkgs.lib.nixosSystem {
        modules = [ {
          nixpkgs.hostPlatform = "x86_64-linux";
          fileSystems."/".device = "/dev/fake";
          boot.loader.grub.enable = false;
        } ];
      };
    };
in
import ./with-inputs.nix outputs

Build output:

$ nix-build -A flake.nixosConfigurations.igloo.config.system.build.toplevel
trace: evaluation warning: system.stateVersion is not set, defaulting to 26.05. Read why this matters on https://nixos.org/manual/nixos/stable/options.html#opt-system.stateVersion.
trace: Obsolete option `dysnomia' is used. It was renamed to `services.dysnomia'.
trace: Obsolete option `jobs' is used. It was renamed to `systemd.services'.
trace: Obsolete option `snapraid' is used. It was renamed to `services.snapraid'.
trace: Obsolete option `system.extraSystemBuilderCmds' is used. It was renamed to `system.systemBuilderCommands'.
trace: Obsolete option `system.forbiddenDependenciesRegex' is used. It was renamed to `system.forbiddenDependenciesRegexes'.
trace: Obsolete option `system.nixosLabel' is used. It was renamed to `system.nixos.label'.
trace: Obsolete option `system.nixosRevision' is used. It was renamed to `system.nixos.revision'.
trace: Obsolete option `system.nixosVersion' is used. It was renamed to `system.nixos.version'.
trace: Obsolete option `system.nixosVersionSuffix' is used. It was renamed to `system.nixos.versionSuffix'.
trace: Obsolete option `system.nssHosts' is used. It was renamed to `system.nssDatabases.hosts'.
trace: Obsolete option `system.replaceRuntimeDependencies' is used. It was renamed to `system.replaceDependencies.replacements'.
/nix/store/xawb45872vjfq2f5i5cr9gqpik3zraav-nixos-system-nixos-26.05.19700101.dirty

$ nix-build -A flake.nixosConfigurations.works.config.system.build.toplevel
trace: evaluation warning: system.stateVersion is not set, defaulting to 26.05. Read why this matters on https://nixos.org/manual/nixos/stable/options.html#opt-system.stateVersion.
/nix/store/cln141bvsdiyqj968mpnssc2mxh5lwvd-nixos-system-nixos-26.05.19700101.dirty

Of course the works machine bypasses Den entirely, so that's not very useful. But, that might indicate that something within Den somehow causes those obsolete prints. I'll try digging further.

Originally posted by @jhakonen in #161 (reply in thread)

[jhakonen]

I wrote a PR that should fix this:
#171