Subject: (require 'tramp) stuck on testing `tramp-ssh-controlmaster-options'

From: 傅文辉 <[email-masked]>
Date: Thu, 17 Sep 2015 10:26:12 +0800

Emacs 24.5.1, tramp 2.2.11-24.5

The following code stuck with some DNS settings

>>> file: tramp-loaddefs.el
(defvar tramp-ssh-controlmaster-options
  ...
  (call-process "ssh" nil t nil "-o" "ControlPath=%C" "host.does.not.exist")
  ...)
<<<

`ssh -o ControlPath=%C host.does.not.exist` stuck instead of going error quickly with DNS from my ISP (both home and workplace).