greek character of GFS Porson is missing with LuaLaTeX (fontspec, polyglossia)

Question

When I LuaLaTeXify a document with GFS Porson as greek font, it doesn't print the Greek semicolon (·) when written as ·, it uses the latin semicolon when written as ;. If I am right, · is \symbol{0387}, which prints nothing, too, the same holds true for \anoteleia. It works with GFS Didot and many other fonts, but not with GFS Porson, though I have all files from TeXlive (in the document: GFSPorson.luc and GFSPorson.otf are used)

PS: With pdflatex (babel ...) there were no problems.

% -*- mode: latex; TeX-engine: luatex; coding: utf-8; -*-
% \RequirePackage{suffix,xstring}
\documentclass{scrbook}
% \RequirePackage{xargs,cmap,xpatch}
% \input{glyphtounicode.tex}\pdfgentounicode=1
\usepackage{luainputenc}
\usepackage{fontspec}
\setmainfont{texgyrepagella-regular.otf}[Style = Alternate, Ligatures = {Common, {TeX}}]
\newfontfamily\greekfont{GFS Porson}[Ligatures = {TeX}]
\usepackage{polyglossia} % babel doesn't help
\setmainlanguage{german}
\setotherlanguage[variant = ancient]{greek}
\usepackage{fixltx2e}
\begin{document}
blablabla 
\selectlanguage{greek}
ΣΩ.\quad Οὑτωσὶ τοίνυν, ὦ παῖ καλέ, ἐννόησον; ὁ μὲν πρότερος ἦν λόγος
Φαίδρου τοῦ Πυθοκλέους, Μυρρινουσίου ἀνδρός\symbol{0387} ὃν δὲ μέλλω λέγειν
Στησιχόρου τοῦ Εὐφήμου, Ἱμεραίου. λεκτέος δὲ ὧδε· ὅτι οὐκ ἔστ’\,ἔτυμος
λόγος ὃς ἂν παρόντος ἐραστοῦ τῷ μὴ ἐρῶντι φῇ δεῖν χαρίζεσθαι\anoteleia{} ὁ
μὲν μαίνεται, ὁ δὲ σωφρονεῖ.
\end{document}

Answer 1

The character exists, provided you use the correct Unicode point (U+0387)

\documentclass{scrbook}
\usepackage{fontspec}
\setmainfont{texgyrepagella-regular.otf}[Style = Alternate, Ligatures = {Common,TeX}]
\newfontfamily\greekfont{GFS Porson}[Ligatures = TeX]

\usepackage{polyglossia}
\setmainlanguage{german}
\setotherlanguage[variant = ancient]{greek}

\begin{document}

\selectlanguage{greek}
Οὑτωσὶ^^^^0387

\end{document}

If you don't need · (U+00B7 MIDDLE DOT) and you're worried about this strange conversion, you can do

\usepackage{newunicodechar}
\newunicodechar{·}{^^^^0387} % the character is U+00B7 MIDDLE DOT

Some more information. It appears that U+00B7 is the “preferred character” in place of U+0387 (the reason is unknown and mysterious to me), so some software seems to arbitrarily do the conversion. The font GFS Porson hasn't been updated like other GFS fonts (Artemisia, Baskerville, Bodoni, Complutum, Didot, Neohellenic and Solomos), so it has nothing in U+00B7.

My Emacs doesn't change the character, so that's why my example compiles correctly, while copying from here doesn't.