Description:
------------
This code is run the apache normal. Nginx and php-fpm in the running error. also in the php-fpm mode ob_flush() has no effect, no immediate output. I think that in two modes should hava the same effect.

Reproduce code:
---------------
<?php
 
for($i = 0; $i < 10; $i++) {
        echo $i."<br />";
        ob_end_flush();
        sleep(1);
}
 
?>

Expected result:
----------------
0
1
2
3
4
5
6
7
8
9


Actual result:
--------------
0
1
Notice: ob_end_flush(): failed to delete and flush buffer. No buffer to delete or flush. in /data/wwwroot/mybook_com/output/flush.php on line 5 2
Notice: ob_end_flush(): failed to delete and flush buffer. No buffer to delete or flush. in /data/wwwroot/mybook_com/output/flush.php on line 5 3
Notice: ob_end_flush(): failed to delete and flush buffer. No buffer to delete or flush. in /data/wwwroot/mybook_com/output/flush.php on line 5 4
Notice: ob_end_flush(): failed to delete and flush buffer. No buffer to delete or flush. in /data/wwwroot/mybook_com/output/flush.php on line 5 5
Notice: ob_end_flush(): failed to delete and flush buffer. No buffer to delete or flush. in /data/wwwroot/mybook_com/output/flush.php on line 5 6
Notice: ob_end_flush(): failed to delete and flush buffer. No buffer to delete or flush. in /data/wwwroot/mybook_com/output/flush.php on line 5 7
Notice: ob_end_flush(): failed to delete and flush buffer. No buffer to delete or flush. in /data/wwwroot/mybook_com/output/flush.php on line 5 8
Notice: ob_end_flush(): failed to delete and flush buffer. No buffer to delete or flush. in /data/wwwroot/mybook_com/output/flush.php on line 5 9
Notice: ob_end_flush(): failed to delete and flush buffer. No buffer to delete or flush. in /data/wwwroot/mybook_com/output/flush.php on line 5