(dired-handle-overwrite): `find-backup-file-name'

may return nil, so handle that.

1 files changed, 10 insertions, 8 deletions

diff --git a/lisp/dired-aux.el b/lisp/dired-aux.el
index dca2ca488ed..69ea15922c4 100644
--- a/lisp/dired-aux.el
+++ b/lisp/dired-aux.el
@@ -925,14 +925,16 @@ Special value `always' suppresses confirmation.")
   ;; Save old version of a to be overwritten file TO.
   ;; `dired-overwrite-confirmed' and `overwrite-backup-query' are fluid vars
   ;; from dired-create-files.
-  (if (and dired-backup-overwrite
-           dired-overwrite-confirmed
-           (or (eq 'always dired-backup-overwrite)
-               (dired-query 'overwrite-backup-query
-                        (format "Make backup for existing file `%s'? " to))))
-      (let ((backup (car (find-backup-file-name to))))
-        (rename-file to backup 0)       ; confirm overwrite of old backup
-        (dired-relist-entry backup))))
+  (let (backup)
+    (if (and dired-backup-overwrite
+             dired-overwrite-confirmed
+             (setq backup (car (find-backup-file-name to)))
+             (or (eq 'always dired-backup-overwrite)
+                 (dired-query 'overwrite-backup-query
+                              (format "Make backup for existing file `%s'? " to))))
+        (progn
+          (rename-file to backup 0)     ; confirm overwrite of old backup
+          (dired-relist-entry backup)))))
 
 ;;;###autoload
 (defun dired-copy-file (from to ok-flag)