check minSeqNo <= maxSeqNo in fetch-manager Enqueue
diff --git a/src/fetch-manager.cc b/src/fetch-manager.cc
index 6d4fb51..1cffa49 100644
--- a/src/fetch-manager.cc
+++ b/src/fetch-manager.cc
@@ -55,6 +55,12 @@
          const SegmentCallback &segmentCallback, const FinishCallback &finishCallback,
          uint64_t minSeqNo, uint64_t maxSeqNo, int priority/*PRIORITY_NORMAL*/)
 {
+  // Assumption for the following code is minSeqNo <= maxSeqNo
+  if (minSeqNo > maxSeqNo)
+  {
+    return;
+  }
+
   // we may need to guarantee that LookupLocator will gives an answer and not throw exception...
   Name forwardingHint;
   forwardingHint = m_mapping (deviceName);