Returns a manifest whose newest epoch matches shards under hrw.
When the newest epoch already describes exactly this shard set with this
algorithm the manifest is returned unchanged, so this is safe to call on
every initialization. Otherwise a new epoch is prepended and the oldest are
dropped past MAX_RETAINED_EPOCHS.
Returns a manifest whose newest epoch matches
shardsunderhrw.When the newest epoch already describes exactly this shard set with this algorithm the manifest is returned unchanged, so this is safe to call on every initialization. Otherwise a new epoch is prepended and the oldest are dropped past MAX_RETAINED_EPOCHS.