fails:String#unpack with format 'N' ignores whitespace in the format string
fails:String#unpack with format 'N' calls #to_str to coerce the directives string
fails:String#unpack with format 'N' adds nil for each element requested beyond the end of the String
fails:String#unpack with format 'n' calls #to_str to coerce the directives string
fails:String#unpack with format 'n' adds nil for each element requested beyond the end of the String
