File README.PACKAGER.xml-commons-external of Package xml-commons

# the external packages in xml-commons are not packed up to date
mkdir external
cd external
svn co -r 406629 http://svn.apache.org/repos/asf/xml/commons/trunk/java/external
find . -name ".svn*" -exec rm -rf {} \;
cp ../xml-commons-externals.tar.bz2 ../xml-commons-externals.tar.bz2.bak
tar -jcf ../xml-commons-externals.tar.bz2 *
cd ..
rm -rf external