> How does that prevent this kind of deadlock?

Like I said, it doesn't:

> even this doesn't fix the root cause because dropping an owned Future isn't guaranteed to cancel it cleanly.

It fixes this:

> However you also wouldn’t be able run use select! in a while loop and try to acquire the same lock (or read from the same channel) without losing your position in the queue.

If you want to fix the root cause, see https://news.ycombinator.com/item?id=45777234