list_children: annotate returned array length
list_children: annotate returned array length

piotras/midgard-core,piotras/midgard-core,midgardproject/midgard-core,midgardproject/midgard-core,midgardproject/midgard-core,midgardproject/midgard-core,piotras/midgard-core,piotras/midgard-core