[metapost] Troubles rendeting text in PNG output

[Akira Kakuto]

Dear Luigi,

> so it looks like a latex issue.

verbatimtex
%&latex
\documentclass[11pt]{article}
\begin{document}
etex

outputformat := "eps";
outputtemplate := "%j-%c.%o";
prologues:=3;
beginfig(1);
label(btex $(hs,f(s)t)$ etex, (0,0));
label(btex \LARGE abracadabra etex, (0,-20));
endfig;
end

The above and the same with
outputformat := "svg";

are OK.

Why the case
outputformat := "png";
is not OK (abracadabra is truncated)?

Best,
Akira