Eelis van der Weegen wrote, on Sun, 30 May 2010 22:48:42 +0200:

Hi Brooks,

I'm mailing you in your capacity as maintainer of the listings package.

I've run into a problem with the listings package running under XeTeX.

When I compile the attached t.tex with xelatex I get the attached t.pdf,
in which the big pi has somehow ended up in front of 'a' instead of
behind it.

I'm using XeTeX 3.1415926-2.2-0.9995.2 as part of TeX Live 2009.

Initially I thought it might have been a problem with XeTeX rather than
listings, but when I mailed to the XeTeX mailing list I was told the
problem is with the listings package:

http://tug.org/pipermail/xetex/2010-May/016840.html

Regards,

Eelis