ovsdb: clean up selectRows() logic and error handling
ovsdb: clean up selectRows() logic and error handling

stevenlin598/quilt,kklin/kelda,PenguinToast/quilt,stevenlin598/quilt,stevenlin598/quilt,kayousterhout/quilt,kklin/quilt,kklin/quilt,mmussomele/quilt,ZhongtianWang/quilt,kklin/quilt,quilt/quilt,kklin/kelda,tejasmanohar/quilt,ejj/quilt-dev,mmussomele/quilt,ejj/quilt-dev,kklin/kelda,kelda/kelda,NetSys/quilt,PenguinToast/quilt,stevenlin598/quilt,quilt/quilt,tejasmanohar/quilt,secant/quilt,PenguinToast/quilt,NetSys/quilt,LuiseV/quilt,ZhongtianWang/quilt,mmussomele/quilt,akshayknarayan/quilt,ZhongtianWang/quilt,LuiseV/quilt,tejasmanohar/quilt,ejj/quilt-dev,kklin/quilt,quilt/quilt,stevenlin598/quilt,NetSys/quilt,secant/quilt,secant/quilt,kelda/kelda,mmussomele/quilt,secant/quilt,LuiseV/quilt,akshayknarayan/quilt,PenguinToast/quilt,kayousterhout/quilt,akshayknarayan/quilt,quilt/quilt,stevenlin598/quilt,tejasmanohar/quilt,kelda/kelda,mmussomele/quilt,LuiseV/quilt,kayousterhout/quilt,kelda/kelda,kklin/kelda,mmussomele/quilt,NetSys/quilt,ejj/quilt-dev,NetSys/quilt,LuiseV/quilt,akshayknarayan/quilt,kayousterhout/quilt,secant/quilt,ZhongtianWang/quilt,PenguinToast/quilt