[metapost] wrong rightward arrow bounding box

[Laurent Méhats]

Hello,

I'm getting a wrong bounding box for the cmr10 rightward arrow: the upper
part of the head lies outside. I've run manually mpto from Tex Live 2008
(mpost version 1.005) and indeed the rule to right is lower than the
arrow. Any idea where this might come from ?

Best regards,
Laurent Méhats

----%<----%<---- test.mp ----%<----%<----%<----%<----%<----%<----%<----
beginfig(0)
draw btex$\rightarrow$etex;
interim bboxmargin:=0;
draw bbox currentpicture;
endfig;
end
----%<----%<---- test.mp ----%<----%<----%<----%<----%<----%<----%<----

----%<----%<---- test.tex ----%<----%<----%<----%<----%<----%<----%<----
\gdef\mpxshipout{\shipout\hbox\bgroup%
  \setbox0=\hbox\bgroup}%
\gdef\stopmpxshipout{\egroup  \dimen0=\ht0 \advance\dimen0\dp0
  \dimen1=\ht0 \dimen2=\dp0
  \setbox0=\hbox\bgroup
    \box0
    \ifnum\dimen0>0 \vrule width1sp height\dimen1 depth\dimen2
    \else \vrule width1sp height1sp depth0sp\relax
    \fi\egroup
  \ht0=0pt \dp0=0pt \box0 \egroup}
\mpxshipout% line 2 test.mp
$\rightarrow$%
\stopmpxshipout
\end{document}
----%<----%<---- test.tex ----%<----%<----%<----%<----%<----%<----%<----