Logging additions; comment about complete propfind issue for future inve...

Capture complete propfinds in the presence of valhalla node sadness. This might kick in to help in case we have more propfind storms. Also, a large comment on what I did to try to reproduce an issue of propfinds to the same directory backing up on each other, which I thought I saw in the logs during the last propfind storm Apr 23, but was unable to reproduce the scenario, so couldn't write code to prevent it. The comment is for future reference in case we encounter another propfind storm and might want to try yet again.