Merge branch 'master' into release_v4.8.1

Author: kuny0707

framework/src/main/java/org/tron/core/db/Manager.java

@@ -881,6 +881,11 @@ public boolean pushTransaction(final TransactionCapsule trx)
       throw new ContractValidateException("ExchangeTransactionContract is rejected");
     }
 
+    if (isExchangeTransaction(trx.getInstance())) {
+      throw new ContractValidateException("ExchangeTransactionContract is rejected");
+    }
+
+
     pushTransactionQueue.add(trx);
     Metrics.gaugeInc(MetricKeys.Gauge.MANAGER_QUEUE, 1,
         MetricLabels.Gauge.QUEUE_QUEUED);