chunks: fix impossible RTT values

Change-Id: Ia7386c6186362be5c50ea291a949fd40ec0224b4
Refs: #4604
diff --git a/tools/chunks/catchunks/pipeline-interests-fixed-window.cpp b/tools/chunks/catchunks/pipeline-interests-fixed-window.cpp
index 53178ee..1794310 100644
--- a/tools/chunks/catchunks/pipeline-interests-fixed-window.cpp
+++ b/tools/chunks/catchunks/pipeline-interests-fixed-window.cpp
@@ -140,9 +140,7 @@
     }
   }
 
-  BOOST_ASSERT(m_nReceived > 0);
-  if (m_hasFinalBlockId &&
-      static_cast<uint64_t>(m_nReceived - 1) >= m_lastSegmentNo) { // all segments have been received
+  if (allSegmentsReceived()) {
     if (!m_options.isQuiet) {
       printSummary();
     }