bug#19702: 25.0.50; Tramp with ssh not working with openssh 6.7 while worked with 6.6

[Michael Albinus]

Filipp Gunbin <fgunbin@fastmail.fm> writes:

Hi Filipp,

> I've recently upgraded openssh to 6.7 on MacOS X (from MacPorts) and ssh
> in Tramp stopped working.  Logs are below.  Activating openssh 6.6
> brings back the working state.
>
> Tramp log buffer:
>
> 17:34:12.318598 tramp-send-command (6) # exec ssh -l root -o
> ControlPath=/var/folders/yb/0cdss5q52d1848_2th2kp_740000gn/T/tramp.587ZOm.%r@%h:%p
> -o ControlMaster=auto -o ControlPersist=no -e none <myhost>
> 17:34:15.933185 tramp-process-actions (6) # 
> root@<myhost>'s password: 
> unix_listener: 
> "/var/folders/yb/0cdss5q52d1848_2th2kp_740000gn/T/tramp.587ZOm.root@<myhost>:22.rIZDlnMe9NViEUbt"
>  too long for Unix domain socket.

You see the error message: the file name of the socket is too long. What
has changed wrt openssh 6.6? Has the template Tramp uses being expanded
differently? And why is there the suffix ".rIZDlnMe9NViEUbt" after the
port number?

As workaround, you could change the template Tramp uses in
`tramp-ssh-controlmaster-options', or you could disable those options
via `tramp-use-ssh-controlmaster-options'.

> Filipp

Best regards, Michael.