>From f8b01ebdbde63d32299f7d0e3290b5b725c48652 Mon Sep 17 00:00:00 2001
From: Andrey Portnoy <aportnoy@fastmail.com>
Date: Tue, 1 Oct 2024 18:29:57 -0400
Subject: [PATCH] Use tramp-optimize-remote-path inside tramp-set-remote-path

---
 lisp/tramp-sh.el | 56 +++++++++++++++++++++++++++++++-----------------
 1 file changed, 36 insertions(+), 20 deletions(-)

diff --git a/lisp/tramp-sh.el b/lisp/tramp-sh.el
index 9e813ecc..1eb3f1c2 100644
--- a/lisp/tramp-sh.el
+++ b/lisp/tramp-sh.el
@@ -4129,6 +4129,9 @@ This function expects to be in the right *tramp* buffer."
 	  (setq result (buffer-substring (point) (line-end-position)))))
     result)))
 
+(defvar tramp-optimize-remote-path t
+  "Whether to remove duplicate and non-existing directories from remote PATH.")
+
 ;; On hydra.nixos.org, the $PATH environment variable is too long to
 ;; send it.  This is likely not due to PATH_MAX, but PIPE_BUF.  We
 ;; check it, and use a temporary file in case of.  See Bug#33781.
@@ -4137,18 +4140,27 @@ This function expects to be in the right *tramp* buffer."
 I.e., for each directory in `tramp-remote-path', it is tested
 whether it exists and if so, it is added to the environment
 variable PATH."
-  (let ((command
-	 (format
-	  "PATH=%s && export PATH"
-	  (string-join (tramp-get-remote-path vec) ":")))
-	(pipe-buf (tramp-get-remote-pipe-buf vec))
-	tmpfile chunk chunksize)
-    (tramp-message vec 5 "Setting $PATH environment variable")
-    (if (length< command pipe-buf)
-	(tramp-send-command vec command)
+  (let* ((should-set-remote-path  ; skip setting remote path in some cases
+	  (or tramp-optimize-remote-path
+	      (not (equal tramp-remote-path '(tramp-own-remote-path)))))
+	 (command
+	  (and should-set-remote-path
+	       (format
+		"PATH=%s && export PATH"
+		(string-join (tramp-get-remote-path vec) ":"))))
+	 (pipe-buf (tramp-get-remote-pipe-buf vec))
+	 tmpfile chunk chunksize)
+    (cond
+     ((not should-set-remote-path)
+      nil)
+     ((length< command pipe-buf)
+      (tramp-message vec 5 "Setting $PATH environment variable")
+      (tramp-send-command vec command))
+     (t
       ;; Use a temporary file.  We cannot use `write-region' because
       ;; setting the remote path happens in the early connection
       ;; handshake, and not all external tools are determined yet.
+      (tramp-message vec 5 "Setting $PATH environment variable")
       (setq command (concat command "\n")
 	    tmpfile (tramp-make-tramp-temp-file vec))
       (while (not (string-empty-p command))
@@ -5610,17 +5622,21 @@ Nonexistent directories are removed from spec."
 		   (cdr elt2)))
 	  (setq remote-path (delq 'tramp-own-remote-path remote-path)))
 
-	;; Remove double entries.
-	(setq remote-path
-	      (cl-remove-duplicates
-	       remote-path :test #'string-equal :from-end t))
-
-	;; Remove non-existing directories.
-	(let (remote-file-name-inhibit-cache)
-	  (tramp-bundle-read-file-names vec remote-path)
-	  (cl-remove-if
-	   (lambda (x) (not (tramp-get-file-property vec x "file-directory-p")))
-	   remote-path))))))
+	(when tramp-optimize-remote-path
+	  ;; Remove double entries.
+	  (setq remote-path
+		(cl-remove-duplicates
+		 remote-path :test #'string-equal :from-end t))
+
+	  ;; Remove non-existing directories.
+	  (let (remote-file-name-inhibit-cache)
+	    (tramp-bundle-read-file-names vec remote-path)
+	    (setq remote-path
+		  (cl-remove-if
+		   (lambda (x)
+		     (not (tramp-get-file-property vec x "file-directory-p")))
+		   remote-path))))
+	remote-path))))
 
 ;; The PIPE_BUF in POSIX [1] can be as low as 512 [2]. Here are the values
 ;; on various platforms:
-- 
2.39.5 (Apple Git-154)