anchor.diff:  
     bashInteractive = appendToName "interactive" (callPackage ../shells/bash {
       interactive = true;
  -    readline = readline63; # Includes many vi mode fixes
     });
   
     bashCompletion = callPackage ../shells/bash-completion { };
  
positive.code: 
    gdb = callPackage ../development/tools/misc/gdb {
      hurd = gnu.hurdCross;
      readline = readline63;
      inherit (gnu) mig;
    };
  
  
negative.code: 
    raul = callPackage ../development/libraries/audio/raul { };
  
    readline = readline6;
    readline6 = readline63;
  
    readline4 = callPackage ../development/libraries/readline/readline4.nix { };
  
    readline5 = callPackage ../development/libraries/readline/readline5.nix { };
  
    readline62 = callPackage ../development/libraries/readline/readline6.nix { };
  
    readline63 = callPackage ../development/libraries/readline/readline6.3.nix { };
  
  