What happens if between 1 and 2 for some reason (system under huge load
or alike) too many time passes? We should prevent expires while the
AOF is loading.
+* #519: Slave may have expired keys that were never read in the master (so a DEL
+ is not sent in the replication channel) but are already expired since
+ a lot of time. Maybe after a given delay that is undoubltly greater than
+ the replication link latency we should expire this key on the slave on
+ access?
DISKSTORE TODO
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