Bug#62046 mysqli@mysqlnd can't iterate over stored sets after call to
mysqli_stmt_reset().
Stmt's state was changed to STMT_PREPARED and leads the driver to think
that the stmt was just prepared. Because result set exist also for only
prepared but not executed sets, the check for stmt->result isn't any good.
There is a result set, because as response for COM_PREPARE the server sends
metadata and metadata is part of a result set. After COM_EXECUTE the server
sends metadata again, which could be different and in this case more correct.
