Description:
------------
create a class which extends the pdo class f.e. "extPDO"
use the persistant mode 
declare a class var f.e. "$sf"
create more then 1 object of the extPDO class and
take access to the class var "$sf"
causes a segmentation fault

no seg fault if:

1. you are NOT in persistant mode
2. you just create 1 instance of the class
2. you don't declare the class var; just set it in the constructor and take access to it

Noticed by accessing two different databases in a loop.

Test script:
---------------
class extPDO extends PDO
{
 public $sf;
 public function  __construct($db_name, $host, $username, $passwd)
 {
  $dsn = 'mysql:dbname='.$db_name.';host='.$host;
  $this->sf = '42';
  $options = array(PDO::ATTR_PERSISTENT => true);
  parent::__construct($dsn, $username, $passwd, $options);
  $this->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
  $this->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
 }
}

function testExtPDO()
{
 for($i = 1; $i <= 2; $i++){
  try{
   $pdo_obj = new extPDO('csp2_mycms', 'csp2-db.pille.hds', 'root', '');
   $sql = 'SELECT user_id FROM user';
   $pdo_st = $pdo_obj->query($sql);
    if($row = $pdo_st->fetch(PDO::FETCH_ASSOC))
     echo $i.'.sf:'. $pdo_obj->sf."<br>";
  }
  catch(Exception $e){
   echo 'Exception: '.$e->getMessage().'<br>';
  }
 }
}
testExtPDO();

Expected result:
----------------
no segmentation fault

Actual result:
--------------
segmentation fault