Comment 37 for bug 186465

After some discussion on #ubuntu+1 (thanks to katad0tls) I *think* this can be triggered by unreachable mirrors. I added a

iptables -A OUTPUT -p tcp --dport 80 -j DROP

rule to a test VM and the updater appeared to be frozen forever. I'm not sure if that is the only way to trigger it (and/or if this is unreleated). I will try to find out more.