tests: improve LpReliability unit tests

count retransmitted, but received packets properly in LpReliability

refs #4391

Change-Id: I6867a70a1e7d7e949a250982df2ff97e49848996
diff --git a/daemon/face/lp-reliability.cpp b/daemon/face/lp-reliability.cpp
index 0df5702..ca5a216 100644
--- a/daemon/face/lp-reliability.cpp
+++ b/daemon/face/lp-reliability.cpp
@@ -265,6 +265,7 @@
   else {
     // Assign new TxSequence
     lp::Sequence newTxSeq = assignTxSequence(txFrag.pkt);
+    netPkt->didRetx = true;
 
     // Move fragment to new TxSequence mapping
     auto newTxFragIt = m_unackedFrags.emplace_hint(