Comment 9 for bug 1101881

While it's trivial to avoid the Traceback, I think the root cause of the crash should be investigated. Looking at the errors page for the crash the majority of the crashes are from armhf systems while there are also some from arm64 and ppc64el.

Given that there are only MirrorsFile information for amd64 and i386 we should maybe just hide the "Download from:" drop down box in software-properties.