fails:ruby -U sets Encoding.default_internal to UTF-8
fails:ruby -U does nothing different if specified multiple times
fails:ruby -U is overruled by Encoding.default_internal=
fails:ruby -U does not affect the default external encoding
fails:ruby -U does not affect the source encoding
fails:ruby -U raises a RuntimeError if used with -Eext:int
fails:ruby -U raises a RuntimeError if used with -E:int
