1 files changed, 19 insertions, 6 deletions

diff --git a/lisp/files.el b/lisp/files.el
index 1a15792c92c..07c2d2c301e 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -787,11 +787,16 @@ the modes of the new file to agree with the old modes."
                                (let ((attr (file-attributes real-file-name)))
                                  (or (nth 9 attr)
                                      (/= (nth 2 attr) (user-uid))))))
-                      (copy-file real-file-name backupname t t)
-; rename-file should delete old backup.
-;                   (condition-case ()
-;                       (delete-file backupname)
-;                     (file-error nil))
+                      (condition-case ()
+                          (copy-file real-file-name backupname t t)
+                        (file-error
+                         ;; If copying fails because file BACKUPNAME
+                         ;; is not writable, delete that file and try again.
+                         (if (and (file-exists-p backupname)
+                                  (not (file-writable-p backupname)))
+                             (delete-file backupname))
+                         (copy-file real-file-name backupname t t)))
+                    ;; rename-file should delete old backup.
                     (rename-file real-file-name backupname t)
                     (setq setmodes (file-modes backupname)))
                 (file-error
@@ -799,7 +804,15 @@ the modes of the new file to agree with the old modes."
                  (setq backupname (expand-file-name "~/%backup%~"))
                  (message "Cannot write backup file; backing up in ~/%%backup%%~")
                  (sleep-for 1)
-                 (copy-file real-file-name backupname t t)))
+                 (condition-case ()
+                     (copy-file real-file-name backupname t t)
+                   (file-error
+                    ;; If copying fails because file BACKUPNAME
+                    ;; is not writable, delete that file and try again.
+                    (if (and (file-exists-p backupname)
+                             (not (file-writable-p backupname)))
+                        (delete-file backupname))
+                    (copy-file real-file-name backupname t t)))))
               (setq buffer-backed-up t)
               ;; Now delete the old versions, if desired.
               (if delete-old-versions