Replication Sequence in Solr 4.2 is
1. Get replicable indexVersion & Generation from Master
2. Fetch File list for given indexVersion and Generation from Master
3. Down the File list
Solr 4.2 and trunk have a Bug, whereby Slave doesn't pass the indexVersion to Master. Master, informs the slave that indexVersion param is missing, but slave ignores it and instead says that there are no filelists to down.
And replication breaks.