Description:
------------
I call a function with a reference to an array and an object.
I then add the object to the end of the array.
When I then use end() and key() to get the key of the the object just added to the array key() always returns 0 rather than the actual key value. 

Reproduce code:
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function addToArray(&$array, $obj)
{
  $array[] = $obj;
  print_r($array);
  end($array);
  print 'last key = '.key($array).'<hr/>';
}

print '<pre>';

$array = array();
for ($a=0; $a<5; $a++)
  addToArray($array, array($a=>$a));

print '</pre>';

Expected result:
----------------
I expect it to print to the screen an array dump followed by the last key value in the array 5 times (seperated by <hr>).
I add an object to the array each time, so the last key value displayed should go from 0 to 4.

Actual result:
--------------
the last key value is always 0 rather than the actual last key value.