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

> From: Sean Whitton <[email protected]>
> Cc: [email protected], [email protected]
> Date: Thu, 30 Jul 2026 11:48:15 +0100
> 
> Eli Zaretskii [30/Jul  7:29am +03] wrote:
> >> Cc: [email protected]
> >> Date: Wed, 29 Jul 2026 18:38:54 +0200
> >> From: Michael Albinus via "Bug reports for GNU Emacs,
> >>  the Swiss army knife of text editors" <[email protected]>
> >>
> >> Shun-ichi TAHARA <[email protected]> writes:
> >>
> >> Hi,
> >>
> >> > 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.
> >>
> >> Yes, this is an undesired side effect of bug#78886.
> >>
> >> > 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.
> >>
> >> It has been fixed with bug#81280. The fix is in master, not in the
> >> emacs-31 branch. It covers also call-process and make-process. Shall we
> >> backport it to Emacs 31? Eli, Sean?
> >
> > Ouch!  I guess we must, since this whole exec-suffixes business is new
> > in Emacs 31.
> >
> > Sean?
> 
> We are discussing backporting the change in dcdd76f89e7, right?
> 
> I think that is okay to backport -- /if/ it introduces problems, they
> are likely to be no worse than what it fixes.

OK, then I'd ask Michael to please cherry-pick it.