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
: "beforeRefresh was called by " + callingThread.getName() + " without a corresponding call to afterRefresh";
                callingThread = Thread.currentThread();
            }
            currentRefreshStartTime = System.nanoTime();
        }
        @Override
        public void afterRefresh(boolean didRefresh) {
            if (Assertions.ENABLED) {
                assert callingThread != null : "afterRefresh called but not beforeRefresh";
                assert callingThread == Thread.currentThread()
                    : "beforeRefreshed called by a different thread. current ["
                        + Thread.currentThread().getName()
                        + "], thread that called beforeRefresh ["
                        + callingThread.getName()
                        + "]";
                callingThread = null;
            }
            refreshMetric.inc(System.nanoTime() - currentRefreshStartTime);
        }
    }
    /**
     * Rollback the current engine to the safe commit, then replay local translog up to the global checkpoint.
     */
    void resetEngineToGlobalCheckpoint() throws IOException {
        assert Thread.holdsLock(mutex) == false : "resetting engine under mutex";
        assert getActiveOperationsCount() == OPERATIONS_BLOCKED
            : "resetting engine without blocking operations; active operations are [" + getActiveOperations() + ']';
        sync(); 
        final SeqNoStats seqNoStats = seqNoStats();
        final TranslogStats translogStats = translogStats();