I don't have my RPi with me to try but I would try the following:
Code
wget http://ftp.us.debian.org/debian/pool/main/x/xmlstarlet/xmlstarlet_1.4.2-1_armel.deb
dpkg -i xmlstarlet_1.4.2-1_armel.deb
Much newer version of xmlstarlet. Maybe it will help. I will try on my RPi tomorrow. Let me know if it helps