Description:
------------
It seems like objects of the same class can access private variables in each other. Access rights check is based on class name instead of reference?

Reproduce code:
---------------
<?php
class strange {
  private $_amount = 10;  
  
  public function foo($other) {
    echo $other->_amount;
    $other->_amount = 666;
  }
}

$t = new strange();
$t->foo(new strange());
?>

Expected result:
----------------
fatal error

Actual result:
--------------
10