Bug#496017: Another backward step. Now the messages are being issued for the first user

[Dominique Brazziel <dbrazziel@snet.net>]

Only user logged in:

Dec 10 16:04:07 dell2400 sshd[8832]: Non-public channel 2, type 1.
Dec 10 16:04:07 dell2400 sshd[8832]: channel_input_success_failure: 2:
unknown 
Dec 10 16:04:22 dell2400 sshd[8832]: Non-public channel 2, type 1.
Dec 10 16:04:22 dell2400 sshd[8832]: channel_input_success_failure: 2:
unknown
Dec 10 16:04:37 dell2400 sshd[8832]: Non-public channel 2, type 1.
Dec 10 16:04:37 dell2400 sshd[8832]: channel_input_success_failure: 2:
unknown
Dec 10 16:04:52 dell2400 sshd[8832]: Non-public channel 2, type 1.
Dec 10 16:04:52 dell2400 sshd[8832]: channel_input_success_failure: 2:
unknown
Dec 10 16:05:07 dell2400 sshd[8832]: Non-public channel 2, type 1.
Dec 10 16:05:07 dell2400 sshd[8832]: channel_input_success_failure: 2:
unknown

I guess that's actually good because it is consistent.  The question is,
what is the intent of logging the message?  It appears to be connected
somehow to ServerAlive and/or ClientAlive (~15 second intervals), and
why is channel type 'SSH_CHANNEL_X11_LISTENER' considered not public?
What would be the effect of adding it to the list of channel types
considered 'OK' by channel_lookup()?