fails:String#unpack with format 'P' round-trips a string through pack and unpack
fails:String#unpack with format 'P' cannot unpack a string except from the same object that created it, or a duplicate of it
fails:String#unpack with format 'P' reads as many characters as specified
fails:String#unpack with format 'P' reads only as far as a NUL character
fails:String#unpack with format 'p' round-trips a string through pack and unpack
fails:String#unpack with format 'p' cannot unpack a string except from the same object that created it, or a duplicate of it
