Comment 2 for bug 746589

I'm assigning to the ubuntuone-control-panel project, since this trace is caused in that source code.

The Ubuntu One control panel uses apt.cache library to query for package availability, but that library is crashing if it can't read a sources file that has some custom/restricted permission set.

I think we should make the control panel robust in this situation so it doesn't break, but we also need that the underlying library handles this case properly.