QuoteValueList for MySql platform fails with multiple empty values.

[OakBehringer]

$db = new \Zend\Db\Adapter\Adapter(array(
    'driver' => 'Pdo',
    'dsn' => 'mysql:dbname=;host='
));

print_r(array(
    $db->platform->quoteValue(null),
    $db->platform->quoteValue(''),
    $db->platform->quoteValueList(array('', null, '', null, '')),
    $db->platform->quoteValueList(array('', '', '')),

));

prints:

Array
(
    [0] => ''
    [1] => ''
    [2] => '', , , , 
    [3] => '', , 
)

You can see that the value list for indexes #2 and 3 are incorrect, only the first values are escaped.

[OakBehringer]

Pull request created for hotfix.

#6839

[turrsis]

This is fixed here 01b9000

[Ocramius]

As @turrsis explained, this was fixed on merge in #5683, though you may still add a test case to prevent a regression (I didn't test this particular bug, I just removed weird looping logic)