diff -r ef1cfc80d51c -r 208c9ac8edbb hooks/syncsources.py
--- a/hooks/syncsources.py	Wed Dec 09 16:15:00 2015 +0100
+++ b/hooks/syncsources.py	Tue Sep 08 09:05:31 2015 +0200
@@ -119,7 +119,7 @@
                 msg = _("You cannot rename the system source")
                 raise validation_error(self.entity, {('name', 'subject'): msg})
             SourceRenamedOp(self._cw, oldname=oldname, newname=newname)
-        if 'config' in self.entity.cw_edited:
+        if 'config' in self.entity.cw_edited or 'url' in self.entity.cw_edited:
             if self.entity.name == 'system' and self.entity.config:
                 msg = _("Configuration of the system source goes to "
                         "the 'sources' file, not in the database")