anchor.diff:  
   
       build =
  -      { tarball ? jobs.tarball {}
  -      , system ? "i686-linux"
  -      }:
  +      { system ? "i686-linux" }:
   
         with import nixpkgs {inherit system;};
   
  
positive.code: 
  
      coverage =
        { tarball ? jobs.tarball {}
        }:
  
        with import nixpkgs {};
  
        releaseTools.coverageAnalysis {
          name = "nix-build";
          src = tarball;
  
          buildInputs = [
            curl perl bzip2 openssl
            # These are for "make check" only:
            graphviz libxml2 libxslt
          ];
  
          configureFlags = ''
            --disable-init-state --disable-shared
            --with-aterm=${aterm} --with-bzip2=${bzip2} --with-sqlite=${sqlite}
          '';
  
          lcovFilter = ["*/boost/*" "*-tab.*"];
  
          # We call `dot', and even though we just use it to
          # syntax-check generated dot files, it still requires some
  
negative.code: { nix ? {outPath = ./.; rev = 1234;}
  , nixpkgs ? ../nixpkgs
  , officialRelease ? false
  }:
  
  let
  
  