fails:IO.open raises an error if passed matching binary/text mode two ways
fails:IO.open raises an error if passed conflicting binary/text mode two ways
windows:IO.open ingores the :encoding option when the :internal_encoding option is present
windows:IO.open raises an Errno::EINVAL if the new mode is not compatible with the descriptor's current mode
fails:IO.open ignores the :encoding option when the :external_encoding option is present
fails:IO.open ignores the :encoding option when the :internal_encoding option is present
fails:IO.open accepts options as keyword arguments
