Do not coredump if pnode=NULL in RelayTransaction

src/net.cpp

@@ -2125,6 +2125,10 @@ void RelayTransaction(const CTransaction& tx, const CDataStream& ss)
     // Only relay to randomly chosen 50% of peers
     BOOST_FOREACH(CNode* pnode, vRelayNodes)
     {
+        //TODO: correct fix is to correctly LOCK vRelayNodes
+        if(!pnode)
+            continue;
+
         if(!pnode->fRelayTxes)
             continue;
         LOCK(pnode->cs_filter);