Don't try to make a pipe process for remote processes in Eshell

Tramp currently isn't able to handle this, so the result will just
produce an error (bug#61024).

* lisp/eshell/esh-proc.el (eshell-gather-process-output): Check for a
remote 'default-directory' before trying to make a pipe process.

* test/lisp/eshell/esh-proc-tests.el
(esh-var-test/output/remote-redirect): New test.

1 files changed, 7 insertions, 2 deletions

diff --git a/lisp/eshell/esh-proc.el b/lisp/eshell/esh-proc.el
index f1ec3a905b6..fcd59ab9f37 100644
--- a/lisp/eshell/esh-proc.el
+++ b/lisp/eshell/esh-proc.el
@@ -296,8 +296,13 @@ Used only on systems which do not support async subprocesses.")
                                                      'unix))))
     (cond
      ((fboundp 'make-process)
-      (unless (equal (car (aref eshell-current-handles eshell-output-handle))
-                     (car (aref eshell-current-handles eshell-error-handle)))
+      (unless (or ;; FIXME: It's not currently possible to use a
+                  ;; stderr process for remote files.
+                  (file-remote-p default-directory)
+                  (equal (car (aref eshell-current-handles
+                                    eshell-output-handle))
+                         (car (aref eshell-current-handles
+                                    eshell-error-handle))))
         (eshell-protect-handles eshell-current-handles)
         (setq stderr-proc
               (make-pipe-process