Channel is not notified, if Connection fails between openChannel and ssh_CHANNEL_OPEN_CONFIRM

[cebewee]

There is a race condition in twisted.conch.ssh.connection.SSHConnection: Since commit 20700, channelClosed ignores half-open channels (openChannel was called, but not yet ssh_CHANNEL_OPEN_CONFIRM). So if channelClosed is called by serviceStopped due to a connection loss, neither ssh_CHANNEL_OPEN_CONFIRM nor ssh_CHANNEL_OPEN_FAILURE is ever called.

So an application expecting either SSHChannel.channelOpen or SSHChannel.openFailed to be called, will wait infinitely. Maybe SSHConnection.channelClosed should call SSHChannel.openFailed in the channel-not-yet-really-open case?

[cebewee]

Change subject to something meaningful.