Fix #3110: _get_leaf_node_ids returns embedded query instead of list
Fix #3110: _get_leaf_node_ids returns embedded query instead of list

lyw07/kolibri,learningequality/kolibri,DXCanas/kolibri,mrpau/kolibri,jonboiser/kolibri,christianmemije/kolibri,christianmemije/kolibri,DXCanas/kolibri,lyw07/kolibri,indirectlylit/kolibri,lyw07/kolibri,jonboiser/kolibri,mrpau/kolibri,learningequality/kolibri,benjaoming/kolibri,mrpau/kolibri,jonboiser/kolibri,learningequality/kolibri,jonboiser/kolibri,mrpau/kolibri,indirectlylit/kolibri,DXCanas/kolibri,benjaoming/kolibri,christianmemije/kolibri,DXCanas/kolibri,indirectlylit/kolibri,indirectlylit/kolibri,lyw07/kolibri,benjaoming/kolibri,learningequality/kolibri,christianmemije/kolibri,benjaoming/kolibri