staticMPfigure problem with \runMP[TEX]graphicsfalse

[Sanjoy Mahajan <sanjoy@mrao.cam.ac.uk>]

Not sure if the following are new behaviors or are the correct ones but
I'm just misunderstanding.  The following jjj.tex file doesn't correctly
generate and include the static metapost figure unless I set
\runMPgraphicstrue and \runMPTEXgraphicstrue in cont-sys.rme and set
shell_escape = t.

If \runMPgraphicsfalse and \runMPTEXgraphicsfalse but shell_escape = t,
then the generated pdf figure is only 1pt wide but is included.  If all
settings are false, then there's a grey square saying 'dummy' etc.

It all works fine if all three settings are true.

But I thought that one can leave all three settings false, and texexec
will still produce the same pdf just with more runs?

This is with context 2006.12.27 (from the Debian context package),
pdftex 1.40.0, metapost 0.993, plus mostly texlive 2005.

=================== begin: jjj.tex ==================
\starttext

\startstaticMPfigure{fig:ellipse}
  path p;
  p := fullcircle scaled 2in yscaled 0.5;
  label(btex hello etex, origin);
  draw p;
\stopstaticMPfigure

\placefigure[right,none]{}{\usestaticMPfigure[fig:ellipse]}

\input tufte

\stoptext
===================   end: jjj.tex ==================

-Sanjoy

`A nation of slaves is always prepared to applaud the clemency of their
 master who, in the abuse of absolute power, does not proceed to the
 last extremes of injustice and oppression.'  (Gibbon)