rest api : query contact -> requested clause 'NOT IN' becomes 'IN'

With REST API (json) if i use a request with 'NOT IN' clause, I get a result as if i had used 'IN'

My POST Param in json format:
json={\"contact_id\":{\"NOT IN\":[1296,1297]}}

Result : I get 2 contacts with ids 1296 and 1297.

---- in the source code civicrm 4.5.2:
CRM_Contact_BAO_query.php line 1827
The 'IN' clause is written in hard :
$this->_where[0][] = "contact_a.id IN ({$idList})";

so 'NOT IN' isn't supported for the array style syntax.