Merge from origin/emacs-24

[gnu-emacs] / lisp / net / tramp.el

diff --git a/lisp/net/tramp.el b/lisp/net/tramp.el
index ba0d13eab8bb31a4a45254dcba2648a76b4ce466..a03affa5eeba3bb8f1a275b30d818cef264ec0cf 100644 (file)
--- a/lisp/net/tramp.el
+++ b/lisp/net/tramp.el
@@ -311,17 +311,26 @@ useful only in combination with `tramp-default-proxies-alist'.")
   (let ((result "")
        (case-fold-search t))
     (ignore-errors
-      (with-temp-buffer
-       (call-process "ssh" nil t nil "-o" "ControlMaster")
-       (goto-char (point-min))
-       (when (search-forward-regexp "missing.+argument" nil t)
-         (setq result "-o ControlPath=%t.%%r@%%h:%%p -o ControlMaster=auto")))
-      (unless (zerop (length result))
+      (when (executable-find "ssh")
        (with-temp-buffer
-         (call-process "ssh" nil t nil "-o" "ControlPersist")
+         (call-process "ssh" nil t nil "-o" "ControlMaster")
          (goto-char (point-min))
          (when (search-forward-regexp "missing.+argument" nil t)
-           (setq result (concat result " -o ControlPersist=no"))))))
+           (setq result "-o ControlMaster=auto")))
+       (unless (zerop (length result))
+         (with-temp-buffer
+           (call-process
+            "ssh" nil t nil "-o" "ControlPath=%C" "host.does.not.exist")
+           (goto-char (point-min))
+           (if (search-forward-regexp "unknown.+key" nil t)
+               (setq result
+                     (concat result " -o ControlPath='tramp.%%r@%%h:%%p'"))
+             (setq result (concat result " -o ControlPath='tramp.%%C'"))))
+         (with-temp-buffer
+           (call-process "ssh" nil t nil "-o" "ControlPersist")
+           (goto-char (point-min))
+           (when (search-forward-regexp "missing.+argument" nil t)
+             (setq result (concat result " -o ControlPersist=no")))))))
     result)
     "Call ssh to detect whether it supports the Control* arguments.
 Return a string to be used in `tramp-methods'.")