"Failed to find node for hop 0 of our path. Discarding this circuit." log spam after guard went down

I noticed this issue with my torperf setup. A tor client that is started with a single node allowed as entry node will freak out if that entry guard goes offline, however briefly.

It keeps logging "Failed to find node for hop 0 of our path. Discarding this circuit." repeatedly, and doesn't seem to recover well at all. I wonder if that means that we are also willing to give up on guards in a regular setup as soon as they go down once, and stop using them.

This might be related to issue #675 (moved)