Code review comment for lp:~takluyver/unattended-upgrades/py3

Thomas, for now I'm going to mark this branch as needs fixing. Please look at my branch, which merges yours into trunk and contains additional fixes that will be necessary. If you can get the remaining tests to pass, I'll be happy to re-review the branch and sponsor it for you.

lp:~barry/unattended-upgrades/py3merge