One more python3 fix.
One more python3 fix.

r23329

joshua-cogliati-inl/raven,idaholab/raven,joshua-cogliati-inl/raven,idaholab/raven,idaholab/raven,joshua-cogliati-inl/raven,idaholab/raven,idaholab/raven,joshua-cogliati-inl/raven,joshua-cogliati-inl/raven,joshua-cogliati-inl/raven,idaholab/raven,idaholab/raven,joshua-cogliati-inl/raven