Merge issue (see attached logs).

When we have

on (A, B and C) and

(on D) merging, the NAKACK information for C might be incorrect due to the fact that D returned a digest containing old information on C.

The issue for UNICAST is similar: D's UNICAST connection table was not cleared for A, B or C because it never received a view change. However, A, B and C cleared their UNICAST connection table of D because they excluded D.

After a merge, D's unicasts to the other partition (and vice versa) will likely fail because D's UNICAST connection tables for A, B and C still contains the old sequence numbers, but the ones for A, B and C start with #1 again !
A possible solution for NAKACK is to verify we handle digests for overlapping partitions OK, and for UNICAST, we'll might have to introduce a seqno agreement protocol, ie. tagging the first seqno as first=true.

A more detailed description will follow.