[metapost] different bounding boxes for identical figures

[Sanjoy Mahajan]

> This was a known bug in metapost 0.641. If you update to teTeX 3.0,
> you will get the newer metapost executable with that bug - and some
> others - fixed.

Thanks, I'll update the mpost somehow.  Although it may need more than
updating the tetex since I'm running 3.0, at least in Debian's
packaging of it.  From "dpkg -l tetex-bin" (tetex-bin has the mpost
binary):

ii  tetex-bin      3.0-13         The teTeX binary files

-Sanjoy

`Never underestimate the evil of which men of power are capable.'
         --Bertrand Russell, _War Crimes in Vietnam_, chapter 1.