fix get incomingedge function for coverageedb
fix get incomingedge function for coverageedb

thomaskrause/graphANNIS,thomaskrause/graphANNIS,thomaskrause/graphANNIS,thomaskrause/graphANNIS,thomaskrause/graphANNIS,thomaskrause/graphANNIS,thomaskrause/graphANNIS