publish: fix backoff
:: if nacked, then set a exponential backoff and retry
=/ nack-count=@ud
+((~(gut by migrate) rid 0))
- ?: (gte 24 nack-count)
+ ?: (gte nack-count 24)
~& >>> "failed to migrate notebook {<rid>} to graph-store"
[~ this]
:_ this(migrate (~(put by migrate) rid nack-count))
