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/indices/recovery/RecoveryState.java
public synchronized void validateCurrentStage(Stage expected) {
        if (stage != expected) {
            assert false : "expected stage [" + expected + "]; but current stage is [" + stage + "]";
            throw new IllegalStateException("expected stage [" + expected + "] but current stage is [" + stage + "]");
        }
    }
    
    public synchronized RecoveryState setStage(Stage stage) {
        switch (stage) {
            case INIT -> {
                
                this.stage = Stage.INIT;
                getIndex().reset();
                getVerifyIndex().reset();
                getTranslog().reset();
            }
            case INDEX -> {
                validateAndSetStage(Stage.INIT, stage);
                getIndex().start();
            }
            case VERIFY_INDEX -> {
                validateAndSetStage(Stage.INDEX, stage);
                getIndex().stop();
                getVerifyIndex().start();
            }
            case TRANSLOG -> {
                validateAndSetStage(Stage.VERIFY_INDEX, stage);
                getVerifyIndex().stop();
                getTranslog().start();
            }