anchor.diff:  
     olinkDB = runCommand "manual-olinkdb"
       { inherit sources;
  -      buildInputs = [ libxml2 libxslt ];
  +      nativeBuildInputs = [ buildPackages.libxml2 buildPackages.libxslt ];
       }
       ''
         xsltproc \
  
positive.code: 
    manual-combined = runCommand "nixos-manual-combined"
      { inherit sources;
        buildInputs = [ libxml2 libxslt ];
        meta.description = "The NixOS manual as plain docbook XML";
      }
      ''
  
negative.code:   # Generate the NixOS manual.
    manual = runCommand "nixos-manual"
      { inherit sources;
        nativeBuildInputs = [ buildPackages.libxml2 buildPackages.libxslt ];
        meta.description = "The NixOS manual in HTML format";
        allowedReferences = ["out"];
      }
  