Use the hiccup mechanism to notify the socket end of the pair of the change in state, and have it shutdown that end, and shutdown the local end normally. This seems to resolve the shutdown and race condition issues.

src/session_base.cpp

@@ -395,15 +395,15 @@ void zmq::session_base_t::detached ()
         return;
     }
 
-    reset ();
-    
     //  For delayed connect situations, terminate the pipe
     //  and reestablish later on
     if (pipe && options.delay_attach_on_connect == 1
         && addr->protocol != "pgm" && addr->protocol != "epgm") {
+        pipe->hiccup ();
         pipe->terminate (false);
-        pipe = NULL;
     }
+
+    reset ();
     
     //  Reconnect.
     if (options.reconnect_ivl != -1)