ENH: added empty input test (good practice)
ENH: added empty input test (good practice)

berendkleinhaneveld/VTK,jmerkow/VTK,spthaolt/VTK,hendradarwin/VTK,sankhesh/VTK,sankhesh/VTK,johnkit/vtk-dev,candy7393/VTK,SimVascular/VTK,jeffbaumes/jeffbaumes-vtk,jeffbaumes/jeffbaumes-vtk,ashray/VTK-EVM,demarle/VTK,keithroe/vtkoptix,sumedhasingla/VTK,candy7393/VTK,demarle/VTK,sumedhasingla/VTK,jmerkow/VTK,gram526/VTK,Wuteyan/VTK,gram526/VTK,ashray/VTK-EVM,aashish24/VTK-old,keithroe/vtkoptix,Wuteyan/VTK,berendkleinhaneveld/VTK,biddisco/VTK,jmerkow/VTK,biddisco/VTK,msmolens/VTK,demarle/VTK,msmolens/VTK,aashish24/VTK-old,demarle/VTK,spthaolt/VTK,daviddoria/PointGraphsPhase1,msmolens/VTK,gram526/VTK,cjh1/VTK,daviddoria/PointGraphsPhase1,mspark93/VTK,collects/VTK,ashray/VTK-EVM,candy7393/VTK,cjh1/VTK,biddisco/VTK,sankhesh/VTK,naucoin/VTKSlicerWidgets,daviddoria/PointGraphsPhase1,arnaudgelas/VTK,hendradarwin/VTK,jmerkow/VTK,collects/VTK,daviddoria/PointGraphsPhase1,arnaudgelas/VTK,cjh1/VTK,biddisco/VTK,arnaudgelas/VTK,Wuteyan/VTK,spthaolt/VTK,hendradarwin/VTK,keithroe/vtkoptix,sankhesh/VTK,jmerkow/VTK,gram526/VTK,SimVascular/VTK,daviddoria/PointGraphsPhase1,jeffbaumes/jeffbaumes-vtk,mspark93/VTK,sankhesh/VTK,mspark93/VTK,candy7393/VTK,cjh1/VTK,msmolens/VTK,keithroe/vtkoptix,jeffbaumes/jeffbaumes-vtk,johnkit/vtk-dev,SimVascular/VTK,naucoin/VTKSlicerWidgets,mspark93/VTK,cjh1/VTK,msmolens/VTK,gram526/VTK,ashray/VTK-EVM,berendkleinhaneveld/VTK,jeffbaumes/jeffbaumes-vtk,sankhesh/VTK,gram526/VTK,hendradarwin/VTK,aashish24/VTK-old,biddisco/VTK,ashray/VTK-EVM,arnaudgelas/VTK,naucoin/VTKSlicerWidgets,keithroe/vtkoptix,aashish24/VTK-old,collects/VTK,naucoin/VTKSlicerWidgets,jmerkow/VTK,demarle/VTK,sumedhasingla/VTK,jmerkow/VTK,ashray/VTK-EVM,johnkit/vtk-dev,sankhesh/VTK,spthaolt/VTK,keithroe/vtkoptix,SimVascular/VTK,berendkleinhaneveld/VTK,demarle/VTK,hendradarwin/VTK,jeffbaumes/jeffbaumes-vtk,gram526/VTK,ashray/VTK-EVM,hendradarwin/VTK,candy7393/VTK,SimVascular/VTK,spthaolt/VTK,biddisco/VTK,candy7393/VTK,demarle/VTK,candy7393/VTK,keithroe/vtkoptix,johnkit/vtk-dev,sankhesh/VTK,mspark93/VTK,berendkleinhaneveld/VTK,naucoin/VTKSlicerWidgets,Wuteyan/VTK,ashray/VTK-EVM,cjh1/VTK,berendkleinhaneveld/VTK,Wuteyan/VTK,aashish24/VTK-old,johnkit/vtk-dev,candy7393/VTK,collects/VTK,msmolens/VTK,hendradarwin/VTK,SimVascular/VTK,berendkleinhaneveld/VTK,daviddoria/PointGraphsPhase1,mspark93/VTK,sumedhasingla/VTK,SimVascular/VTK,aashish24/VTK-old,SimVascular/VTK,sumedhasingla/VTK,Wuteyan/VTK,Wuteyan/VTK,arnaudgelas/VTK,johnkit/vtk-dev,sumedhasingla/VTK,collects/VTK,jmerkow/VTK,mspark93/VTK,demarle/VTK,msmolens/VTK,biddisco/VTK,keithroe/vtkoptix,gram526/VTK,mspark93/VTK,msmolens/VTK,naucoin/VTKSlicerWidgets,johnkit/vtk-dev,sumedhasingla/VTK,collects/VTK,spthaolt/VTK,arnaudgelas/VTK,sumedhasingla/VTK,spthaolt/VTK