Bookie recovery should skip replicating empty ledgers.

[ivankelly]

JIRA: https://issues.apache.org/jira/browse/BOOKKEEPER-979

Reporter: Sijie Guo @sijie

Skip replicating empty ledgers.

Comments from JIRA

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Matteo Merli 2016-11-28T22:24:43.105+0000

I tried to fix this some time back, but it was causing errors on the replication unit tests and eventually I had to revert the change.

This was the diff: https://gist.github.com/merlimat/c09c0a1ce3a9817196d8481f89023461

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Yiming Zang 2016-11-28T22:34:45.641+0000

I think I have a similar fix in our internal branch, we should be able to merge back to community soon.

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Sijie Guo 2017-07-28T00:03:59.844+0000

move replication related changes to 4.6.0

[ivankelly]

@jiazhai @sijie @merlimat @yzang
Bump this to 4.8.0?