Shards unassigned after datanode addition

[DavidTurner]

The primary was on a node with ID B2GcZ5KFRG23IMePeJWA4g a couple of days ago:

@viratag26

"unassigned_info": {
    "reason": "NODE_LEFT",
    "at": "2019-07-16T05:01:51.383Z",
    "details": "node_left[B2GcZ5KFRG23IMePeJWA4g]",

This node no longer has any trace of this shard:

@viratag26

{
      "node_id": "B2GcZ5KFRG23IMePeJWA4g",
      "node_name": "dxb-dso01-nec-nfvi2-cmn-nec-celshd01.nfvi.localdomain",
      "transport_address": "172.17.41.145:9300",
...
      "store": {
        "found": false
      }

I think you have done something more destructive than simply adding a node to this cluster, because that would not cause what we're seeing here.