fix topic on displayhook in ZMQShell

IPython/zmq/displayhook.py

@@ -43,6 +43,7 b' class ZMQShellDisplayHook(DisplayHook):'
     """A displayhook subclass that publishes data using ZeroMQ. This is intended
     to work with an InteractiveShell instance. It sends a dict of different
     representations of the object."""
+    topic=None
 
     session = Instance(Session)
     pub_socket = Instance('zmq.Socket')
@@ -67,6 +68,6 b' class ZMQShellDisplayHook(DisplayHook):'
         """Finish up all displayhook activities."""
         sys.stdout.flush()
         sys.stderr.flush()
-        self.session.send(self.pub_socket, self.msg)
+        self.session.send(self.pub_socket, self.msg, ident=self.topic)
         self.msg = None
 

IPython/zmq/ipkernel.py

@@ -145,6 +145,7 b' class Kernel(Configurable):'
         )
         self.shell.displayhook.session = self.session
         self.shell.displayhook.pub_socket = self.iopub_socket
+        self.shell.displayhook.topic = self._topic('pyout')
         self.shell.display_pub.session = self.session
         self.shell.display_pub.pub_socket = self.iopub_socket
 

IPython/zmq/zmqshell.py

@@ -183,7 +183,11 b' class ZMQInteractiveShell(InteractiveShell):'
         dh = self.displayhook
         # Send exception info over pub socket for other clients than the caller
         # to pick up
-        exc_msg = dh.session.send(dh.pub_socket, u'pyerr', json_clean(exc_content), dh.parent_header)
+        topic = None
+        if dh.topic:
+            topic = dh.topic.replace(b'pyout', b'pyerr')
+        
+        exc_msg = dh.session.send(dh.pub_socket, u'pyerr', json_clean(exc_content), dh.parent_header, ident=topic)
 
         # FIXME - Hack: store exception info in shell object.  Right now, the
         # caller is reading this info after the fact, we need to fix this logic