Users should be able to upload a python file containing a PyNN script. But at the moment, they can't.
Here is what I experienced:
(1) The interface for brain model upload is not clear: which kind of files should we upload?
(2) Uploading a python file doesn't work: an error says that one should upload a .zip file instead
(3) Loading a .zip file fails with the error you reported.
Thanks for your report, the issue will be assigned soon.