Skip ownership iteration when there's no owner.
Skip ownership iteration when there's no owner.

There's no point in iterating over all the nodes and assigning ownership if
there's no owner to begin with.

YorickPeterse/oga,YorickPeterse/oga,ttasanen/oga,altmetric/oga,jeffreybaird/oga,altmetric/oga,ttasanen/oga,altmetric/oga,jeffreybaird/oga,jeffreybaird/oga,ttasanen/oga,altmetric/oga,YorickPeterse/oga,YorickPeterse/oga,jeffreybaird/oga,jeffreybaird/oga,ttasanen/oga,YorickPeterse/oga,dfockler/oga,dfockler/oga,dfockler/oga,dfockler/oga,dfockler/oga,altmetric/oga,ttasanen/oga