FIX: Python testing was saving foo_1.valid.png style files
FIX: Python testing was saving foo_1.valid.png style files

This causes an issue as CTest looks for foo.valid.png

Change-Id: Ia8e809f20c72ce42a20f08e896cf4550191cff71

sumedhasingla/VTK,keithroe/vtkoptix,demarle/VTK,sankhesh/VTK,SimVascular/VTK,jmerkow/VTK,sankhesh/VTK,keithroe/vtkoptix,jmerkow/VTK,mspark93/VTK,sankhesh/VTK,johnkit/vtk-dev,mspark93/VTK,demarle/VTK,johnkit/vtk-dev,ashray/VTK-EVM,demarle/VTK,keithroe/vtkoptix,mspark93/VTK,candy7393/VTK,jmerkow/VTK,candy7393/VTK,jmerkow/VTK,candy7393/VTK,hendradarwin/VTK,SimVascular/VTK,candy7393/VTK,johnkit/vtk-dev,jmerkow/VTK,candy7393/VTK,keithroe/vtkoptix,keithroe/vtkoptix,gram526/VTK,sumedhasingla/VTK,hendradarwin/VTK,candy7393/VTK,johnkit/vtk-dev,candy7393/VTK,johnkit/vtk-dev,keithroe/vtkoptix,mspark93/VTK,ashray/VTK-EVM,msmolens/VTK,demarle/VTK,johnkit/vtk-dev,keithroe/vtkoptix,mspark93/VTK,SimVascular/VTK,hendradarwin/VTK,mspark93/VTK,demarle/VTK,johnkit/vtk-dev,gram526/VTK,keithroe/vtkoptix,ashray/VTK-EVM,ashray/VTK-EVM,ashray/VTK-EVM,demarle/VTK,gram526/VTK,gram526/VTK,msmolens/VTK,gram526/VTK,msmolens/VTK,msmolens/VTK,candy7393/VTK,sumedhasingla/VTK,gram526/VTK,mspark93/VTK,msmolens/VTK,jmerkow/VTK,sankhesh/VTK,msmolens/VTK,hendradarwin/VTK,hendradarwin/VTK,sankhesh/VTK,SimVascular/VTK,sumedhasingla/VTK,sumedhasingla/VTK,SimVascular/VTK,jmerkow/VTK,SimVascular/VTK,sankhesh/VTK,gram526/VTK,sankhesh/VTK,ashray/VTK-EVM,sankhesh/VTK,mspark93/VTK,gram526/VTK,hendradarwin/VTK,msmolens/VTK,sumedhasingla/VTK,hendradarwin/VTK,SimVascular/VTK,demarle/VTK,jmerkow/VTK,sumedhasingla/VTK,msmolens/VTK,SimVascular/VTK,ashray/VTK-EVM,ashray/VTK-EVM,demarle/VTK,sumedhasingla/VTK