add special case for emit_body that checks for root node
add special case for emit_body that checks for root node

cucapra/braid,guoyiteng/braid,cucapra/braid,guoyiteng/braid,cucapra/braid,guoyiteng/braid,cucapra/braid,guoyiteng/braid,guoyiteng/braid,cucapra/braid,guoyiteng/braid,cucapra/braid