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
for (FileDetail file : fileDetails.values()) {
                if (file.reused()) {
                    reused++;
                }
            }
            return reused;
        }
        public synchronized long reusedBytes() {
            long reused = 0;
            for (FileDetail file : fileDetails.values()) {
                if (file.reused()) {
                    reused += file.length();
                }
            }
            return reused;
        }
        @Override
        public synchronized XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
            
            builder.startObject(Fields.SIZE);
            builder.humanReadableField(Fields.TOTAL_IN_BYTES, Fields.TOTAL, new ByteSizeValue(totalBytes()));
            builder.humanReadableField(Fields.REUSED_IN_BYTES, Fields.REUSED, new ByteSizeValue(reusedBytes()));
            builder.humanReadableField(Fields.RECOVERED_IN_BYTES, Fields.RECOVERED, new ByteSizeValue(recoveredBytes()));
            builder.humanReadableField(
                Fields.RECOVERED_FROM_SNAPSHOT_IN_BYTES,
                Fields.RECOVERED_FROM_SNAPSHOT,
                new ByteSizeValue(recoveredFromSnapshotBytes())
            );
            builder.field(Fields.PERCENT, String.format(Locale.ROOT, "%1.1f%%", recoveredBytesPercent()));
            builder.endObject();