Description:
------------
When I  terminate a script by an exit,
before end  of execution, ob_start allows to 
to invoke a callback function.
From this callback function, I cannot access to an 
object (in source example:$t1) previously initiated in the script. 
However, if I save a dummy copy of that object in a new variable (for instance $t2), then it work as expected.
In the source example, just uncomment the line "$t2=$t1;"
to see what I mean.
I works normally in previous version of php (php 4 and first releases of 5)
I cannot remplace the exit at the end by an ob_flush(), because I'm including a big script in my real work, which is much more complex than the example I provide.

Reproduce code:
---------------
<?php
class test{
	function nice_string(){
		 return "hello world, how are you ?";
	}	
}
$t1 =  new test();

// the following commented line makes a difference 
//$t2=$t1;

function callbackfunc($output){
	 global $t1;	 		
   $output ="chocolate<br>". $output . "<br>". $t1->nice_string();     
  	return "$output";
}
ob_start('callbackfunc');
echo "what a nice day";
exit();  ?>

Expected result:
----------------
should output:
chocolate
what a nice day
hello world, how are you ?

Actual result:
--------------
output nothing,
blank page,
probably a fatal error without any indication about it.

Uncommenting line $t2=$t1 and it works fine again.