With pdflatex, this

```
\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[main=british,polutonikogreek]{babel}
\begin{document}
{\selectlanguage{polutonikogreek}
οὔ μοι τὰ Γύγεω τοῦ πολυχρύσου μέλει,}
he said
\end{document}

```

yields the expected, and I suppose the Greek font is cbgreek.
But with lualatex, the Greek disappears. What must I change to
get the same output with lualatex as with pdflatex?