* eshell/em-unix.el (eshell/su): Require tramp.

(eshell/sudo): Require tramp.  Remove now unnecessary check.

* net/tramp-sh.el (tramp-sh-handle-start-file-process): Let-bind
`tramp-current-connection' in order to avoid an error when several
commands are invoked in a short time in eshell and friends.

lisp/ChangeLog

+2013-02-18  Michael Albinus  <michael.albinus@gmx.de>
+
+	* eshell/em-unix.el (eshell/su): Require tramp.
+	(eshell/sudo): Require tramp.  Remove now unnecessary check.
+
+	* net/tramp-sh.el (tramp-sh-handle-start-file-process): Let-bind
+	`tramp-current-connection' in order to avoid an error when several
+	commands are invoked in a short time in eshell and friends.
+
 2013-02-16  Didier Verna  <didier@didierverna.net>
 	* net/network-stream.el (network-stream-open-starttls):

lisp/eshell/em-unix.el

@@ -1039,6 +1039,7 @@ Show wall-clock time elapsed during execution of COMMAND.")
 
 (defun eshell/su (&rest args)
   "Alias \"su\" to call Tramp."
+  (require 'tramp)
   (setq args (eshell-stringify-list (eshell-flatten-list args)))
   (let ((orig-args (copy-tree args)))
     (eshell-eval-using-options
@@ -1076,6 +1077,7 @@ Become another USER during a login session.")
 
 (defun eshell/sudo (&rest args)
   "Alias \"sudo\" to call Tramp."
+  (require 'tramp)
   (setq args (eshell-stringify-list (eshell-flatten-list args)))
   (let ((orig-args (copy-tree args)))
     (eshell-eval-using-options
@@ -1110,8 +1112,6 @@ Execute a COMMAND as the superuser or another USER.")
 			  (format "%s|sudo:%s@%s:%s"
 				  (substring prefix 0 -1) user host dir)
 			(format "/sudo:%s@%s:%s" user host dir))))
-		;; Ensure, that Tramp has connected to that construct already.
-		(ignore (file-exists-p default-directory))
 		(eshell-named-command (car orig-args) (cdr orig-args))))))))
 
 (put 'eshell/sudo 'eshell-no-numeric-conversions t)

lisp/net/tramp-sh.el

@@ -2739,7 +2739,11 @@ the result will be a local, non-Tramp, filename."
 	   (or (null program) tramp-process-connection-type))
 	  (bmp (and (buffer-live-p buffer) (buffer-modified-p buffer)))
 	  (name1 name)
-	  (i 0))
+	  (i 0)
+	  ;; We do not want to raise an error when
+	  ;; `start-file-process' has been started several time in
+	  ;; `eshell' and friends.
+	  (tramp-current-connection nil))
 
       (unless buffer
 	;; BUFFER can be nil.  We use a temporary buffer.