Why does my svn:externals folder not get included in my egg?

Question

I've got a project structure as follows:

ProjFolder\project\  
                   |__init__.py
                   |main.py  
                   |...  
                   |data\  
                         |settings.dtd  
                         |archs\  
                                |arch1.arc  
                                ...

Under the folder project there are a few more modules, and the folder project\data\archs is an svn:external prop on the folder data. I've got a setuptools setup.py in the ProjFolder which is correctly grabbing all the modules and the DTD's under data, but not the archs folder. I've tried explicitly adding the files to package_data instead of using include_package_data = True, the current state is:

...
packages = find_packages('project'),
package_dir = {'' : 'project'},

package_data = {
    '' : ['*.dtd', '*.png'],
    'project' : ['data/*', 'data/archs/*.*']},
...

This still doesn't work though. I haven't found anything via google or stack overflow that would suggest that svn:externals are disallowed, but maybe this is something coming from distutils that everyone else just knows? Any help at getting this working greatly appreciated!

---

I may have jumped the gun blaming the svn:externals bit, but I had just read a bit of setuptools and it talked about subversion and so on... I did manage to get the egg to be built correctly by including the data files through a data_files directive instead of package_data.