FIX: added extra check for swapping callbacks in destructor.
FIX: added extra check for swapping callbacks in destructor.

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