Description:
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According to http://bugs.mysql.com/bug.php?id=61656 mysql bug PDO::quote() method shouldn't change ' to \' for mysql driver. Should change for ''.

Test script:
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<?php 

$tmp = "Let's go!";
$pdo = new PDO("mysql:host=localhost;initStatements=SET NAMES utf8;model=mysql4;type=pdo_mysql;pdoType=;active=1", 'root', '', array());
echo $pdo->quote($tmp);

?>

Expected result:
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'Let''s go!'

Actual result:
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'Let\'s go!'