Description:
------------
Using php 5.3.5 with pdo_pgsql and pgsql 9.0.2 when inserting serialized objects 
that contain private variables the serialized string is truncate as soon as it 
hits the private variable.

Objects that do not contain private variables work fine.

When using the pdo_mysql driver it also works fine.

Test script:
---------------
<?php
class foo{
private $_var;
}
$foo=serialize(new foo());
$q=new PDO("pgsql:host=localhost;dbname=testdb","root","");
$q->exec('CREATE TABLE test (data TEXT)');
$s=$q->prepare("INSERT INTO test VALUES(?)");
$s->bindValue(1,$foo);
$s->execute();
$s=$q->query("SELECT * FROM test");
var_dump($s->fetchAll(PDO::FETCH_ASSOC),$foo);

Expected result:
----------------
array(1) {
  [0]=>
  array(1) {
    ["data"]=>
    string(32) "O:3:"foo":1:{s:9:"foo_var";N;}"
  }
}
string(32) "O:3:"foo":1:{s:9:"foo_var";N;}"


Actual result:
--------------
array(1) {
  [0]=>
  array(1) {
    ["data"]=>
    string(18) "O:3:"foo":1:{s:9:""
  }
}
string(32) "O:3:"foo":1:{s:9:"foo_var";N;}"