bug#42125: Python mode load failing due to some issue with tramp

[Eric S. Raymond]

Package: emacs
Version: 26.3

Python mode load is failing due to some issue with tramp.  Likely a
loaddefs issue or something similar.  To reproduce, simply visit
a file with a .py extension.

Stack trace:

Debugger entered--Lisp error: (void-variable tramp-default-user-alist)
  (member x tramp-default-user-alist)
  (if (member x tramp-default-user-alist) tramp-default-user-alist (setq 
tramp-default-user-alist (cons x tramp-default-user-alist)))
  (let* ((x (cons (concat "\\`" (regexp-opt (quote ("su" "sudo" "doas" "ksu"))) 
"\\'") (quote (nil "root"))))) (if (member x tramp-default-user-alist) 
tramp-default-user-alist (setq tramp-default-user-alist (cons x 
tramp-default-user-alist))))
  eval-buffer(#<buffer  *load*-849947> nil 
"/usr/share/emacs/26.3/lisp/net/tramp-sh.el" nil t)  ; Reading at buffer 
position 15068
  load-with-code-conversion("/usr/share/emacs/26.3/lisp/net/tramp-sh.el" 
"/usr/share/emacs/26.3/lisp/net/tramp-sh.el" nil t)
  require(tramp-sh)
  eval-buffer(#<buffer  *load*> nil 
"/usr/share/emacs/26.3/lisp/progmodes/python.el" nil t)  ; Reading at buffer 
position 12340
  load-with-code-conversion("/usr/share/emacs/26.3/lisp/progmodes/python.el" 
"/usr/share/emacs/26.3/lisp/progmodes/python.el" nil t)
  python-mode()
  set-auto-mode-0(python-mode nil)
  set-auto-mode()
  normal-mode(t)
  after-find-file(nil t)
  find-file-noselect-1(#<buffer irkerhook.py> "~/WWW/irker/irkerhook.py" nil 
nil "~/public_html/irker/irkerhook.py" (5771543 66307))
  find-file-noselect("~/WWW/irker/irkerhook.py" nil nil t)
  find-file("~/WWW/irker/irkerhook.py" t)
  funcall-interactively(find-file "~/WWW/irker/irkerhook.py" t)
  call-interactively(find-file nil nil)
  command-execute(find-file)

There's a workaround: deleting (require 'tramp-sh) from early in
python.el. Of course this disables some remote features.
-- 
                <a href="http://www.catb.org/~esr/";>Eric S. Raymond</a>

"They that can give up essential liberty to obtain a little temporary 
safety deserve neither liberty nor safety."
        -- Benjamin Franklin, Historical Review of Pennsylvania, 1759.