_IO_wfile_underflow_mmap error/eof case

[Roland McGrath]

It seems to me that:

      fp->_flags |= _IO_EOF_SEEN;

in _IO_wfile_underflow_mmap is wrong.  In that case,
_IO_file_underflow_mmap has already set either the EOF or ERROR flag bit.
If there was an error rather than EOF, the EOF bit should not be set too.
Am I missing something or should I remove this line?