hello-protocol: set canBePrefix to true

refs: #4691, #4679

Change-Id: I5f57d7bb6a75af074fc64206fe6061f2fc758b40
diff --git a/src/hello-protocol.cpp b/src/hello-protocol.cpp
index 34600a7..079bdc4 100644
--- a/src/hello-protocol.cpp
+++ b/src/hello-protocol.cpp
@@ -45,6 +45,7 @@
   ndn::Interest i(interestName);
   i.setInterestLifetime(ndn::time::seconds(seconds));
   i.setMustBeFresh(true);
+  i.setCanBePrefix(true);
   m_nlsr.getNlsrFace().expressInterest(i,
                                        std::bind(&HelloProtocol::onContent,
                                                  this,