This allows for watchers to be created concurrently
without needing potentially complex and latency-adding
queuing on the client.
Signed-off-by: Gyuho Lee <gyuhox@gmail.com>
Current tests don't normally trigger the watch victim path because the
constants are too large; set the constants to small values and hammer
the store to cause watch delivery delays.
Makes w.cur into w.minrev, the minimum revision for the next update, and
retries cancelation if the watcher isn't found (because it's being processed
by moveVictims).
Fixes: #5459
