anchor.diff:  
   with lib;
   
  -{ pname
  +{ /*
  +    pname: Nix package name without special symbols and without version or
  +    "emacs-" prefix.
  +  */
  +  pname
  +  /*
  +    ename: Original Emacs package name, possibly containing special symbols.
  +  */
  +, ename ? pname
   , version
   , recipe
   , meta ? {}
  
positive.code:   installPhase = ''
      runHook preInstall
  
      archive="$NIX_BUILD_TOP/packages/$pname-$version.el"
      if [ ! -f "$archive" ]; then
          archive="$NIX_BUILD_TOP/packages/$pname-$version.tar"
      fi
  
      emacs --batch -Q \
  
negative.code: 
    postUnpack = ''
      mkdir -p "$NIX_BUILD_TOP/working"
      ln -s "$NIX_BUILD_TOP/$sourceRoot" "$NIX_BUILD_TOP/working/$ename"
    '';
  
    buildPhase =
  