apt downloads do not disconnect

[tkluck-booking]

I've observed that when apt downloads indexes or packages, it gets stuck at 100% download, waiting for a timeout instead of proceeding to download the next package.

My hypothesis is that pac4cli does not properly disconnect the apt -> pac4cli connection when the pac4cli -> server connection is being dropped by the server.

This is when downloading over http. I haven't validated whether it's using CONNECT or just GET, but I suspect the latter.

[tkluck-booking]

Should probably validate whether the twisted package / us properly adhere to this spec here.

[tkluck]

-> #37