[Twisted-Python] KeyError in SSHConnection.ssh_CHANNEL_OPEN_CONFIRMATION

[Stephen McRoberts]

I'm looking for suggestions why the channel key would be missing after it was just opened.
I use persistent connections with a timeout but the timer is reset every call so it stays open.

Here's some of my logs:

2017-07-05 15:26:45-0500 [-] opening channel 4 with 65536 32768
2017-07-05 15:36:45-0500  [SSHService 'ssh-connection' on ClientTransport,client] Unhandled Error
--- (snipped traceback for clarity) ---
File "/usr/local/lib/python2.7/dist-packages/twisted/conch/ssh/connection.py", line 180, in ssh_CHANNEL_OPEN_CONFIRMATION
   channel = self.channels[localChannel]
   exceptions.KeyError: 4

The same connection instance will work later on the next channel so it seems the connection is fine.

Any suggestions on what would cause this behavior?

Is this behavior typical?