Minimal updates to pure Python kernel to keep it (somewhat) API compatible with the IPython Kernel.

We should define a basic interface for Kernel objects so that we do not continue to have these problems.

IPython/zmq/pykernel.py

@@ -36,6 +36,12 b' from session import Session, Message'
 
 class Kernel(HasTraits):
 
+    # Private interface
+
+    # This is a dict of port number that the kernel is listening on. It is set
+    # by record_ports and used by connect_request.
+    _recorded_ports = None
+
     #---------------------------------------------------------------------------
     # Kernel interface
     #---------------------------------------------------------------------------
@@ -75,6 +81,19 b' class Kernel(HasTraits):'
             else:
                 handler(ident, omsg)
 
+    def record_ports(self, xrep_port, pub_port, req_port, hb_port):
+        """Record the ports that this kernel is using.
+
+        The creator of the Kernel instance must call this methods if they
+        want the :meth:`connect_request` method to return the port numbers.
+        """
+        self._recorded_ports = {
+            'xrep_port' : xrep_port,
+            'pub_port' : pub_port,
+            'req_port' : req_port,
+            'hb_port' : hb_port
+        }
+
     #---------------------------------------------------------------------------
     # Kernel request handlers
     #---------------------------------------------------------------------------