> I think we don't want to do this elif branch. Later we do gaussian_deviate.setSigma(...), which would change the value of sigma in the input rng, which seems like bad form. We should leave the settings alone on any provided rng.
> 
Oooh.  Good catch.  I just fixed this (see commit that I pushed).  It's an issue both for RealGalaxy and InterpolatedImage so I fixed both.