PARAM_INT_ARRAY / PARAM_STR_ARRAY depends of parameter order

Named parameters appears to be treated as ordered parameters, when using PARAM_INT_ARRAY or PARAM_STR_ARRAY:

$query = $em->createQuery('
SELECT f FROM Foo f
WHERE a = :a
AND b IN (:b)
');

$query->setParameters(array(
    'b' => array(1,2,3),
    'a' => 1,
));

Notice that in the query the parameter :a appears before :b. And I call ->setParameters() with :b before :a.

When running this, I get an error from Doctrine/DBAL/SQLParserUtils::expandListParameters:119 saying that the second parameter of array_merge() is not an array.

When setting the parameters in the same order than they appear in the query, it works:

$query->setParameters(array(
    'a' => 1,
    'b' => array(1,2,3),
));

This is unexpected, as I'm using named parameters; the order should not matter.