"Low circuit success rate %u/%u for guard %s=%s."

I'm seeing this "low circuit success rate" warning on my client sometimes when on a flaky wireless network connection.

I'm guessing that the problem is that we're blaming the guard when we should in fact be blaming the network.

We should a) figure out how to improve the log message so we get more hints about where our bug is, and/or b) just straight-out hunt for it.

Mike suggests raising the number of circuits we have to make before we'll spit out the warning. I expect that will mask the bug, but not find or resolve it.

Bug report originally raised in #7066 (moved).