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.
x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/xpack/searchablesnapshots/recovery/SearchableSnapshotRecoveryState.java
}
        return super.setStage(stage);
    }
    @Override
    public synchronized RecoveryState setRemoteTranslogStage() {
        remoteTranslogSet = true;
        super.setStage(Stage.TRANSLOG);
        return super.setStage(Stage.FINALIZE);
    }
    @Override
    public synchronized void validateCurrentStage(Stage expected) {
        if (remoteTranslogSet == false) {
            super.validateCurrentStage(expected);
        } else {
            final Stage stage = getStage();
            
            
            if (stage != Stage.FINALIZE && stage != Stage.DONE) {
                assert false : "expected stage [" + Stage.FINALIZE + " || " + Stage.DONE + "]; but current stage is [" + stage + "]";
                throw new IllegalStateException(
                    "expected stage [" + Stage.FINALIZE + " || " + Stage.DONE + "]; " + "but current stage is [" + stage + "]"
                );
            }
        }
    }
    
    boolean isRemoteTranslogSet() {
        return remoteTranslogSet;
    }
    public synchronized void setPreWarmComplete() {