+ /**
+ * fd_event is around while we have async requests outstanding or are
+ * building a chained request.
+ *
+ * (fd_event!=NULL) &&
+ * ((outstanding_request!=NULL)||(chain_accumulator!=NULL))
+ *
+ * should always be true, as well as the reverse: If both cli_request
+ * pointers are NULL, no fd_event is around.
+ */