anchor.diff:  
   let
   
  +  version = builtins.readFile ./.version;
     versionSuffix = "pre${toString nixosSrc.rev}-${toString nixpkgs.rev}";
   
   
  
positive.code: 
      with import <nixpkgs> {inherit system;};
      let
        version = builtins.readFile ./.version + (lib.optionalString (!officialRelease) versionSuffix);
  
        versionModule = { system.nixosVersion = version; };
  
        config = (import lib/eval-config.nix {
          inherit system;
  
negative.code:       releaseTools.makeSourceTarball {
          name = "nixos-tarball";
  
          src = nixosSrc;
  
          inherit officialRelease version;
  
          distPhase = ''
            echo -n $VERSION_SUFFIX > .version-suffix
  