Split-brain: cancelled ST results in missing data

1. Cluster [A, B, C, D], in CH 1 segment X owned by [D, C]
2. Split brain [A, B], [C, D]: A and B detects that D is missing, therefore they get view [A, B, C] and start rebalancing, in CH 2 segment X is owned by [C, B]
3. A and B get new view [A, B] (C is missing) and state transfer of X is cancelled, nodes enter degraded mode.
4. Split brain is fixed, all nodes find each other and merge - B starts to be AVAILABLE, but still does not have data for X
5. Subsequent requests on B return null upon cache.get()