Problem with decimal numbersystem

Hello,

The decimal number system implemented in MetaPost (mplib?) seems to be bugged. If I execute this LuaLaTeX program

\documentclass{article}
\usepackage{luamplib}
	\mplibnumbersystem{decimal}
\begin{document}
	\begin{mplibcode}
		beginfig(1);
			label(decimal 1/3, origin);
		endfig;
	\end{mplibcode}
\end{document}

I get this message in the console:

lualatex(1899,0x7fff7af13300) malloc: *** error for object 0x200007fb93320000: pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug
Abort

It seems more of a luatex/mplib/lua problem, since the corresponding metapost program:

beginfig(1);
	label(decimal 1/3, origin);
endfig;
end.

executed with « mpost — numbersystem=decimal », works flawlessly.

Any idea of what is going wrong here ?

I’m using TeX Live 2017 (from MacTeX), LuaTeX version 1.0.4 and MetaPost 2.00.

Thanks in advance,

Franck Pastor
--
http://tug.org/metapost/