Contrary to what tony2001 says in #40604, this was actually working fine until it 
was broken in 5.2

http://3v4l.org/SUUkK

The reason that http://3v4l.org/pZ2PP works might be explained to the second 
reference to the same object which could prevent destruction, but that would then 
actually be a bug too (since it indicates a memory-leak).

Yes, I agree that there might be two bugs here. 

Here's another test script that shows that this only affects objects and not 
other data types.

http://3v4l.org/Ip5Sn
<?php

function output($buffer) {
  global $object, $string, $int, $float, $array;

  $ret_val = array($string, $object->bar, $int, sprintf("%.2f", $float), 
$array[0]);
  return implode(" ", $ret_val);
}

ob_start('output');

$object = new stdClass();
$object->bar = "bar";

$string = "foo";
$int = 1;
$float = 2.0;
$array = array('array');

// $test = $object;
?>

Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php

So something has to be shut down first, it's kind of a chicken and egg problem.
Object destruction is performed in two stages, objects with e.g. circular 
references are destroyed at the very last (try $object->ref=$object to see the 
difference).