anchor.diff:  
   
     # Extract name with version from URL. Ask for separator which is
  -  # supposed to start extension
  -  nameFromURL = url: sep: let
  -    components = splitString "/" url;
  -    filename = lib.last components;
  -    name = builtins.head (splitString sep filename);
  -  in
  -  assert ! eqStrings name filename;
  -  name;
  +  # supposed to start extension.
  +  nameFromURL = url: sep:
  +    let
  +      components = splitString "/" url;
  +      filename = lib.last components;
  +      name = builtins.head (splitString sep filename);
  +    in assert name !=  filename; name;
   
   
     # Create an --{enable,disable}-<feat> string that can be passed to
  
positive.code:   enableFeature = enable: feat: "--${if enable then "enable" else "disable"}-${feat}";
  
  
    # Create a fixed width string with additional prefix to match required width
    fixedWidthString = width: filler: str:
      let
        strw = lib.stringLength str;
  
negative.code:       if strw == width then str else filler + fixedWidthString reqWidth filler str;
  
  
    # Format a number adding leading zeroes up to fixed width.
    fixedWidthNumber = width: n: fixedWidthString width "0" (toString n);
  }
  