Comment 19 for bug 1571174

I don't seem to be able to reproduce the original bug. This is likely due to the dpkg fix in 1.18.4ubuntu1.1 that has already landed. However we know that there could exist edge cases that would still cause an upgrade failure without the Breaks clause, so I think this SRU is still worth landing. I have verified that, with squid installed, I can upgrade to xenial-proposed from wily (using apt-get dist-upgrade after manipulating sources.list).