don't abort queue on execution failure

This causes many problems, and should be reconsidered.
Disable for now, as it is necessary for the Kernel merge.

IPython/zmq/ipkernel.py

@@ -405,7 +405,10 b' class Kernel(Configurable):'
         self.log.debug("%s", reply_msg)
 
         if reply_msg['content']['status'] == u'error':
-            self._abort_queues()
+            # FIXME: queue_abort on error is disabled
+            # A policy decision must be made
+            pass
+            # self._abort_queues()
 
         self.session.send(self.iopub_stream,
                           u'status',