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
Engine engine,
        long seqNo,
        long opPrimaryTerm,
        long version,
        String id,
        @Nullable VersionType versionType,
        long ifSeqNo,
        long ifPrimaryTerm,
        Engine.Operation.Origin origin
    ) throws IOException {
        assert opPrimaryTerm <= getOperationPrimaryTerm()
            : "op term [ " + opPrimaryTerm + " ] > shard term [" + getOperationPrimaryTerm() + "]";
        ensureWriteAllowed(origin);
        final Engine.Delete delete = prepareDelete(id, seqNo, opPrimaryTerm, version, versionType, origin, ifSeqNo, ifPrimaryTerm);
        return delete(engine, delete);
    }
    public static Engine.Delete prepareDelete(
        String id,
        long seqNo,
        long primaryTerm,
        long version,
        VersionType versionType,
        Engine.Operation.Origin origin,
        long ifSeqNo,
        long ifPrimaryTerm
    ) {
        long startTime = System.nanoTime();
        final Term uid = new Term(IdFieldMapper.NAME, Uid.encodeId(id));
        return new Engine.Delete(id, uid, seqNo, primaryTerm, version, versionType, origin, startTime, ifSeqNo, ifPrimaryTerm);
    }