Problem with dql, filter and global search

[veolys-nanne]

I have entities with binded comments. A comment can be important depending on a flag.
So, I write a custom dql to get a column indicating if the entity contains at last one important comment (could be a BooleanColumn):

$this->columnBuilder
    ->add('has_important_comment', Column::class, array(
        'title' => 'Has important comment',
        'dql' => '(SELECT (CASE WHEN COUNT({c}) > 0 THEN 1 ELSE 0 END) FROM MyBundle:Comment {c} WHERE {c}.entity = entity AND {c}.important = true)',
        'searchable' => true,
    ));

I add a select filter on this column:

$this->columnBuilder
    ->add('has_important_comment', Column::class, array(
        'title' => 'Has important comment',
        'dql' => '(SELECT (CASE WHEN COUNT({c}) > 0 THEN 1 ELSE 0 END) FROM MyBundle:Comment {c} WHERE {c}.entity = entity AND {c}.important = true)',
        'searchable' => true,
        'filter' => [
            SelectFilter::class,
            [
                'search_type' => 'eq',
                'select_options' => ['' => 'Any', '1' => 'Yes', '0' => 'No'],
            ],
        ],
    ));              

It works as expected. I can filter all entities with at last one important comment or all entities with none important comment.
But with global search and filter, both activated, I've got a bug as the dql is used twice in condition.
{c} is replaced by c_search in the LIKE condition for the global search and again by c_search in the eq/Select condition.