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
assert assertPrimaryMode();
        verifyNotClosed();
        ensureSoftDeletesEnabled();
        replicationTracker.removeRetentionLease(id, listener);
    }
    /**
     * Updates retention leases on a replica.
     *
     * @param retentionLeases the retention leases
     */
    public void updateRetentionLeasesOnReplica(final RetentionLeases retentionLeases) {
        assert assertReplicationTarget();
        verifyNotClosed();
        replicationTracker.updateRetentionLeasesOnReplica(retentionLeases);
    }
    /**
     * Loads the latest retention leases from their dedicated state file.
     *
     * @return the retention leases
     * @throws IOException if an I/O exception occurs reading the retention leases
     */
    public RetentionLeases loadRetentionLeases() throws IOException {
        verifyNotClosed();
        return replicationTracker.loadRetentionLeases(path.getShardStatePath());
    }
    /**
     * Persists the current retention leases to their dedicated state file.
     *
     * @throws WriteStateException if an exception occurs writing the state file
     */