bug#81517: 31.0.90; executable-find on remote buffer fails

After Emacs31.0.90 with Windows, executable-find on remote buffer
returns nil.  Then, for example, save-buffers on remote file using tramp
fails because '(executable-find "pscp")' returns nil; I use "pscp.exe"
derivered from PuTTY and it is expected that the exe file is found by
executable-find.

I found that tramp added '(exec-suffixes . (""))' to tramp-connection-
local-default-system-variables at tramp-integration.el since Emacs31.
So 'exec-suffixes' is always changed to that value on remote buffer.

It harms because suffixes are disabled even when local executables are
required; "pscp.exe" installed in local file systems must be found then.

I suppose it might be a bug of tramp.
Emacs-31.0.91 has the same problem, also the same with git HEAD.

Regards.


In GNU Emacs 31.0.90 (build 2, x86_64-w64-mingw32) of 2026-06-10 built
  on AVALON
Windowing system distributor 'Microsoft Corp.', version 10.0.26200
System Description: Microsoft Windows 10 Pro (v10.0.2009.26200.8875)

Configured using:
  'configure --prefix=/h/install/emacs-31.0.90
  --enable-checking=yes,glyphs --disable-acl --with-modules
  --without-dbus --without-compress-install --with-native-compilation=aot
  'CFLAGS=-O0 -g3''

Configured features:
GIF GMP GNUTLS HARFBUZZ JPEG LCMS2 LIBXML2 MODULES NATIVE_COMP NOTIFY
W32NOTIFY PDUMPER PNG RSVG SOUND SQLITE3 THREADS TIFF
TOOLKIT_SCROLL_BARS TREE_SITTER WEBP XPM ZLIB

(NATIVE_COMP present but libgccjit not available)

Important settings:
   value of $LANG: JPN
   locale-coding-system: cp932

Major mode: Lisp Interaction

Minor modes in effect:
   marginalia-mode: t
   fido-vertical-mode: t
   icomplete-vertical-mode: t
   icomplete-mode: t
   fido-mode: t
   corfu-history-mode: t
   global-corfu-mode: t
   corfu-mode: t
   display-line-numbers-mode: t
   highlight-indent-guides-mode: t
   whitespace-mode: t
   highlight-quoted-mode: t
   highlight-defined-mode: t
   volatile-highlights-mode: t
   delete-selection-mode: t
   ruler-mode: t
   server-mode: t
   pixel-scroll-precision-mode: t
   global-auto-revert-mode: t
   global-so-long-mode: t
   tooltip-mode: t
   global-eldoc-mode: t
   eldoc-mode: t
   show-paren-mode: t
   electric-indent-mode: t
   mouse-wheel-mode: t
   tool-bar-mode: t
   menu-bar-mode: t
   file-name-shadow-mode: t
   global-font-lock-mode: t
   font-lock-mode: t
   minibuffer-nonselected-mode: t
   minibuffer-regexp-mode: t
   column-number-mode: t
   line-number-mode: t
   transient-mark-mode: t
   auto-composition-mode: t
   auto-encryption-mode: t
   auto-compression-mode: t

Load-path shadows:
c:/Local/Emacs/share/emacs/site-lisp/lua-mode hides 
c:/Local/Emacs/share/emacs/31.0.90/lisp/progmodes/lua-mode

Features:
(shadow sort mail-extr emacsbug lisp-mnt message mailcap yank-media puny
dired dired-loaddefs rfc822 mml mml-sec epa derived epg rfc6068
epg-config gnus-util mm-decode mm-bodies mm-encode mailabbrev gmm-utils
mailheader sendmail mail-parse rfc2231 rfc2047 rfc2045 ietf-drums
mm-util mail-prsvr mail-utils marginalia icomplete orderless
corfu-history corfu-auto easy-mmode web-capf cape-keyword cape corfu
compat display-line-numbers highlight-indent-guides color whitespace
highlight-quoted highlight-defined w32-ime tr-ime-debug
tr-ime-documentfeed tr-ime-reconversion tr-ime-sync tr-ime-prefix-key
tr-ime-workaround-isearch tr-ime-isearch tr-ime-font tr-ime-recv-notify
tr-ime-thread-message tr-ime-subclassify tr-ime-hook tr-ime-openstatus
tr-ime-modadv tr-ime treesit warnings etags fileloop generator xref
text-property-search project advice volatile-highlights delsel keybind
misclib tramp-cmds tramp-cache time-stamp tramp trampver
tramp-integration files-x tramp-message help-mode tramp-compat xdg shell
pcomplete comint ansi-osc parse-time iso8601 time-date format-spec
auth-source cl-seq eieio eieio-core cl-macs gv password-cache json map
ansi-color tramp-loaddefs rx cus-edit pp cus-start cus-load icons
wid-edit ruler-mode jka-compr server pixel-scroll ring subr-x mule-util
autorevert filenotify so-long cl-loaddefs cl-lib init-fontset japan-util
rmc iso-transl tooltip cconv eldoc paren electric uniquify ediff-hook
vc-hooks lisp-float-type elisp-mode mwheel touch-screen dos-w32 ls-lisp
term/w32-nt disp-table term/w32-win w32-win w32-vars term/common-win
tool-bar dnd fontset image regexp-opt fringe tabulated-list replace
newcomment text-mode lisp-mode prog-mode register page tab-bar menu-bar
rfn-eshadow isearch easymenu timer select scroll-bar mouse jit-lock
font-lock syntax font-core term/tty-colors frame minibuffer nadvice seq
simple cl-generic indonesian philippine cham georgian utf-8-lang
misc-lang vietnamese tibetan thai tai-viet lao korean japanese eucjp-ms
cp51932 hebrew greek romanian slovak czech european ethiopic indian
cyrillic chinese composite emoji-zwj charscript charprop case-table
epa-hook jka-cmpr-hook help abbrev obarray oclosure cl-preloaded button
loaddefs theme-loaddefs faces cus-face macroexp files window
text-properties overlay sha1 md5 base64 format env code-pages mule
custom widget keymap hashtable-print-readable backquote threads
w32notify w32 lcms2 multi-tty move-toolbar make-network-process
tty-child-frames native-compile emacs)

Memory information:
((conses 16 159014 70317) (symbols 48 15423 1) (strings 32 45813 2516)
  (string-bytes 1 1661981) (vectors 16 60806)
  (vector-slots 8 1147322 103024) (floats 8 223 36)
  (intervals 56 884 161) (buffers 1064 10))
-- 
Shun-ichi Tahara
mailto:[email protected]