Sender doesn't guarantee anything about pos, this doesn't seem to work on Win32 host

nel/src/net/unified_network.cpp

@@ -268,7 +268,12 @@ void	uncbServiceIdentification(CMessage &msgin, TSockId from, CCallbackNetBase &
 
 	if (isExternal)
 	{
+
+#ifdef NL_OS_WINDOWS
+		pos = 0;
+#else
 		nlassert(pos == 0);
+#endif
 	}
 
 	if (inSid.get() == 0)