fix(filer.backup): local sink readonly permission (#8907)

weed/replication/sink/localsink/local_sink.go

@@ -93,7 +93,11 @@ func (localsink *LocalSink) CreateEntry(key string, entry *filer_pb.Entry, signa
 	}
 
 	mode := os.FileMode(entry.Attributes.FileMode)
-	dstFile, err := os.OpenFile(util.ToShortFileName(key), os.O_RDWR|os.O_CREATE|os.O_TRUNC, mode)
+	shortFileName := util.ToShortFileName(key)
+	if err := os.Remove(shortFileName); err != nil && !os.IsNotExist(err) {
+		return err
+	}
+	dstFile, err := os.OpenFile(shortFileName, os.O_RDWR|os.O_CREATE|os.O_TRUNC, mode)
 	if err != nil {
 		return err
 	}