[metapost] mptopdf: font map entry warnings in TeXLive 2009

[Oliver Buerschaper]

Hi,

running a MetaPost file with mptopdf from a freshly installed TeXLive  
2009 (on Mac OS X 10.5.8) yields a ton of warnings like this one:

Warning: fontmap entry for `ASCII' already exists, duplicates ignored

While these warnings barely slow down the program in the Terminal, in  
TeXShop there's a huge impact on compilation speed :-(

What can I do to avoid the warnings?

Best,
Oliver