fw: implement self-learning forwarding strategy

refs #4279

Change-Id: I3c80820f9e3382d204a75ea3248234581b4d97d2
diff --git a/daemon/fw/forwarder.cpp b/daemon/fw/forwarder.cpp
index d55da5a..b53b82d 100644
--- a/daemon/fw/forwarder.cpp
+++ b/daemon/fw/forwarder.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2018,  Regents of the University of California,
+ * Copyright (c) 2014-2019,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -515,6 +515,7 @@
 void
 Forwarder::setExpiryTimer(const shared_ptr<pit::Entry>& pitEntry, time::milliseconds duration)
 {
+  BOOST_ASSERT(pitEntry);
   BOOST_ASSERT(duration >= 0_ms);
 
   scheduler::cancel(pitEntry->expiryTimer);