If two shards differ we need to sync
If two shards differ we need to sync

There's no security if two shards return different answers but it gives
us enough of a signal to know that we need to trigger a full on
synchronization.

BugzId: 18955

fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb