> could I request that we mention this procedure in the config documentation Wiki? It does mean that in the else: case the noise model in the output is somewhat (very, very slightly admittedly) different from that specified by the user, so we ought not to do it completely silently.

Yes.  Good idea.  I'll add some discussion about it under the `whiten` keyword.  Note: it's even more true about pure Poisson noise.  At least for CCDNoise, some of the Gaussian white noise gets to be applied to the read_noise which is Gaussian.