[test, cw props] ensure we can't add user specific / system-wide properties
we had this pb on an historical instance in our intranet (eg. running
for about 8 years).
Document: cubicweb-doc
Title: CubicWeb documentation
Author: Logilab
Abstract: Some base documentation for CubicWeb users and developpers
Section: Apps/Programming
Format: HTML
Index: /usr/share/doc/cubicweb-documentation/index.html
Files: /usr/share/doc/cubicweb-documentation/*.html