Posted a design for [[design/balanced_preferred_content]]. This would let
preferred content expressions assign each file to N repositories out of a
group, selected using Math. Adding a repository could optionally be
configured to automatically rebalance the files (not very bandwidth
efficiently though). I think some have asked for a feature like this
before, so read the design and see if it would be useful for you.

Spent a while debugging a problem with a S3 remote, which seems to have
been a misconfiguration in the end. But several improvements came out of
it to make it easier to debug S3 in the future etc.
