Rebalance exited with reason replicator_died ( after upgrade?)

build 1419
step:
1. previously it was cluster with 1409 build
2.upgrade nodes 10.3.121.115,10.3.121.116,10.3.121.112,10.3.121.113,10.3.121.1154( build 1416)
(aboout 11.5M docs in the cluster)
3. during about 9 hours run 2 view queries in parallel and performed docs ops:
pytests/performance/mcsoda.py membase://10.3.121.112:8091 max-creates=12000000 json=1 doc-gen=0 doc-cache=0 ratio-creates=0 ratio-deletes=0.1 vbuckets=1024 ratio-sets=0.01 started at 4 am, 8 4. failover 10.3.121.113 and rebalance cluster

result:
Rebalance exited with reason {exited,
{'EXIT',<0.12686.17>,
{replicator_died,
{'EXIT',<15292.3521.374>,normal}}}}