Description:
------------
During script termination, PHP's explicit output buffer flush should wait until all variables have gone -completely- out of scope. Using an instantiated object that manages buffers, the data has already been flushed before __destruct() is called, which prevents the script from properly finalizing data collection and flushing the output normally. This is not the appropriate behavior.

Reproduce code:
---------------
<?php

error_reporting(E_ALL);


class Example
{
    function __construct()
    {
        ob_start();
        echo 'This should be displayed last.'."\n";
    }

    function __destruct()
    {
        $buffered_data = ob_get_contents();
        ob_end_clean();

        echo 'This should be displayed first.'."\n";
        echo 'Buffered data: '. $buffered_data;
    }
}


$obj = new Example;

?>

Expected result:
----------------
This should be displayed first.
Buffered data: This should be displayed last.

Actual result:
--------------
This should be displayed last.

Notice: ob_end_clean(): failed to delete buffer. No buffer to delete. in /--snip--/test.php on line 17
This should be displayed first.
Buffered data: