Backport commit 18e1455c8 from Emacs

* lisp/ox-texinfo.el (org-texinfo-export-to-texinfo-batch):
Overwrite existing output.

Make generation of texi from org overwrite output
18e1455c8ae851791a047dc56eef972cc24e5b6c
Glenn Morris
Sun Feb 28 15:13:07 2021 -0800

lisp/ox-texinfo.el

@@ -1629,17 +1629,16 @@ Return output file's name."
 
 (defun org-texinfo-export-to-texinfo-batch ()
   "Export Org file INFILE to Texinfo file OUTFILE, in batch mode.
+Overwrites existing output file.
 Usage: emacs -batch -f org-texinfo-export-to-texinfo-batch INFILE OUTFILE"
   (or noninteractive (user-error "Batch mode use only"))
   (let ((infile (pop command-line-args-left))
 	(outfile (pop command-line-args-left))
-	(org-export-coding-system org-texinfo-coding-system))
+	(org-export-coding-system org-texinfo-coding-system)
+        (make-backup-files nil))
     (unless (file-readable-p infile)
       (message "File `%s' not readable" infile)
       (kill-emacs 1))
-    (when (file-exists-p outfile)
-      (message "File `%s' already exists" outfile)
-      (kill-emacs 1))
     (with-temp-buffer
       (insert-file-contents infile)
       (org-export-to-file 'texinfo outfile))))