Fix spurious error message
Fix spurious error message

-  in FeatureGroove, the check for multiple
   solids in result was checking the wrong
   variable.

Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master