[luatex] newlines in key-value list

[Ulrike Fischer]

In the following example using the variable A to get a key val list
gives and error (` color` not a key). Obviously because of the
newline in the string definition (B works fine). How can I avoid it?


\documentclass{scrartcl}
\usepackage{chessboard}
\usepackage{luacode}
\begin{document}
\begin{luacode}

A=[[color=green,
    color=red]]

B=[[color=green, color=red]]
\end{luacode}

\chessboard[\directlua{tex.sprint(A)}]

\chessboard[\directlua{tex.sprint(B)}]

\end{document}

-- 
Ulrike Fischer