The OverseerCollectionMessageHandler sliceCmd assumes only one replica exists on one node
When multiple replicas of a slice are on the same node we only track one replica's async request. This happens because the async requestMap's key is "node_name"
I discovered this when alabax shared some logs of a restore issue, where the second replica got added before the first replica had completed it's restorecore action.
While looking at the logs I noticed that the overseer never called REQUESTSTATUS for the restorecore action , almost as if it had missed tracking that particular async request.