BUG: It is possible in some circumstances for a Python observer callback to be called after the interpreter has been finalized causing a segfault.  This patch ensures that the interpreter is alive before calling the callback preventing these problems.
BUG: It is possible in some circumstances for a Python observer callback
to be called after the interpreter has been finalized causing a
segfault.  This patch ensures that the interpreter is alive before
calling the callback preventing these problems.

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