Do not try to send notifications on closed connections

Now we can assert that abort is not called when it shouldn't be.

git-svn-id: https://svn.erp5.org/repos/neo/trunk@2728 71dcc9de-d417-0410-9af5-da40c76e7ee4

neo/lib/connection.py

@@ -180,11 +180,9 @@ class HandlerSwitcher(object):
         else:
             neo.lib.logging.error(
                             'Unexpected answer %r in %r', packet, connection)
+            if not connection.isClosed():
                 notification = Packets.Notify('Unexpected answer: %r' % packet)
-            try:
                 connection.notify(notification)
-            except ConnectorConnectionClosedException:
-                pass
                 connection.abort()
             handler.peerBroken(connection)
         # apply a pending handler if no more answers are pending
@@ -476,6 +474,7 @@ class Connection(BaseConnection):
         """Abort dealing with this connection."""
         neo.lib.logging.debug('aborting a connector for %r', self)
         self.aborted = True
+        assert self.write_buf
 
     def writable(self):
         """Called when self is writable."""