Comment 8 for bug 843752

In the scenario where JOINER and DONOR have diverged but still have the same cluster UUID, and JOINER seqno < DONOR seqno, you are right that at this point we cannot detect that JOINER state is different from the corresponding historical DONOR state. However, if IST then proceeds, and JOINER continues to XOR a checksum of each transaction into it's state information, by the time the seqno is equal on both sides, the checksum is not, and we can reliably detect split brain.