Description:
------------
PDO MySQL driver does not escape backslashes in string.

The MySQL doc indicates that backslashes must be doubled to be escaped 
http://dev.mysql.com/doc/refman/5.6/en/string-literals.html

The driver does not do that. See the script above.
Should this escaping be done by PDO or a higher layer like Doctrine DBAL?

Test script:
---------------
<?php

define('DSN', 'mysql:dbname=testdb;host=127.0.0.1');
define('USER', 'root');
define('PASSWORD', '');

/* DATABASE STRUCTURE

CREATE TABLE `test` (
  `test` varchar(255) NOT NULL,
  PRIMARY KEY (`test`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

*/

$dbh = new PDO(DSN, USER, PASSWORD);

$data = '\\' . uniqid();

$stmt = $dbh->prepare('INSERT INTO test(test) VALUES(:data)');
$stmt->execute(array('data' => $data));


$stmt = $dbh->prepare('SELECT test FROM test WHERE test LIKE :data');
$stmt->execute(array('data' => $data));

var_dump($stmt->fetchColumn());

$stmt = $dbh->prepare('SELECT test FROM test WHERE test LIKE :data');
$stmt->execute(array('data' =>  str_replace('\\', '\\\\', $data)));

var_dump($stmt->fetchColumn());


Expected result:
----------------
string(14) "\521f3f450f597"
bool(false)

Actual result:
--------------
bool(false)
string(14) "\521f3f450f597"