emacs-28 0a2507f: Backport: Make a more robust check in Tramp using scripts

[Michael Albinus]

branch: emacs-28
commit 0a2507ff9095bb725e8c30017c413840c11ff132
Author: Michael Albinus <michael.albinus@gmx.de>
Commit: Michael Albinus <michael.albinus@gmx.de>

    Backport: Make a more robust check in Tramp using scripts
    
    * lisp/net/tramp-sh.el (tramp-find-inline-encoding):
    Check, whether scripts in `tramp-remote-coding-commands' are
    expandable.
    
    (cherry picked from commit 1d0a60113fd155c77ef5ea4ea44fcba3504adcbf)
---
 lisp/net/tramp-sh.el | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lisp/net/tramp-sh.el b/lisp/net/tramp-sh.el
index 6f3b324..2121738 100644
--- a/lisp/net/tramp-sh.el
+++ b/lisp/net/tramp-sh.el
@@ -4585,6 +4585,8 @@ Goes through the list `tramp-local-coding-commands' and
                          (value (symbol-value rem-enc)))
                      (while (string-match "-" name)
                        (setq name (replace-match "_" nil t name)))
+                     (unless (tramp-expand-script vec value)
+                       (throw 'wont-work-remote nil))
                      (tramp-maybe-send-script vec value name)
                      (setq rem-enc name)))
                  (tramp-message
@@ -4602,6 +4604,8 @@ Goes through the list `tramp-local-coding-commands' and
                          (value (symbol-value rem-dec)))
                      (while (string-match "-" name)
                        (setq name (replace-match "_" nil t name)))
+                     (unless (tramp-expand-script vec value)
+                       (throw 'wont-work-remote nil))
                      (tramp-maybe-send-script vec value name)
                      (setq rem-dec name)))
                  (tramp-message