bug#17653: 24.3; Tramp doesn't detect ssh ControlMaster

[Michael Albinus <michael.albinus@gmx.de>]

Juliusz Chroboczek <jch@pps.univ-paris-diderot.fr> writes:

> (tramp-detect-ssh-controlmaster)
> nil
> (call-process "ssh" nil t nil "-o" "ControlMaster")
> command-line line 0: missing argument.
> 255
>
> The issue is that tramp-detect-ssh-controlmaster looks for the fixed
> string "Missing ControlMaster argument", while my version of ssh returns
> a differently worded error message.

In the current pretest of Emacs 24.4 as well in recent Tramp versions,
the defun `tramp-detect-ssh-controlmaster' is replaced by a defconst
`tramp-ssh-controlmaster-options'. The defcustom
`tramp-use-ssh-controlmaster-options' controls whether you use it.

> On a related note -- there doesn't seem to be a way of working around that
> without resorting to advice, there's no defvar to tweak.

The native way to fix this in Tramp is tweaking `tramp-methods'. Add a
new method "myssh" with your preferred arguments.

Confirmed, `tramp-methods' is under-documented. I could guide you in
case of problems.

> -- Juliusz

Best regards, Michael.