With a content pool of eight, all eight downloads wait at once. Photo 103's
is answered 404 and the line reporting it throws while the other seven
still wait. When lib.backup() rejects, the other seven originals must be in
place and the lock gone, so nothing is written after the backup has ended.
Today the backup rejects as soon as that one worker throws, before the
others have written anything.
Model: opus-5-5
sneak
7339199be8
