We saw a case where the recovery stats reported `recovered_bytes` greater than `length_in_bytes` for one file:

```
GET /_recovery?detailed

200 OK
...
{
  "name": "_buk.fdt",
  "length_in_bytes": 26891307173,
  "reused": false,
  "recovered_in_bytes": 35324928266,
  "recovered_from_snapshot_in_bytes": 8433621093
}
...
```

NB `35324928266 == 26891307173 + 8433621093`

This causes Elasticsearch to compute a negative value for the reserved space on the target node of this recovery, which prevents stats APIs from working. This appears to be caused by a network-level failure which triggers a retry without first cancelling an ongoing download of a different file with the same name from the snapshot repository.

---

### Workaround

Restart the target node to clear these stats.
server/src/main/java/org/elasticsearch/index/shard/IndexShard.java
getEngine().refresh("post_recovery");
            synchronized (mutex) {
                if (state == IndexShardState.CLOSED) {
                    throw new IndexShardClosedException(shardId);
                }
                if (state == IndexShardState.STARTED) {
                    throw new IndexShardStartedException(shardId);
                }
                recoveryState.setStage(RecoveryState.Stage.DONE);
                changeState(IndexShardState.POST_RECOVERY, reason);
            }
        }
    }
    /**
     * called before starting to copy index files over
     */
    public void prepareForIndexRecovery() {
        if (state != IndexShardState.RECOVERING) {
            throw new IndexShardNotRecoveringException(shardId, state);
        }
        recoveryState.setStage(RecoveryState.Stage.INDEX);
        assert currentEngineReference.get() == null;
    }
    /**
     * A best effort to bring up this shard to the global checkpoint using the local translog before performing a peer recovery.
     *