(find-backup-file-name): delete nothing if overflow in number of files to keep.

1 files changed, 4 insertions, 1 deletions

diff --git a/lisp/files.el b/lisp/files.el
index b8cb0a0ea5c..fe3a29cfdd1 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -1141,7 +1141,10 @@ Value is a list whose car is the name for the backup file
       (if (not deserve-versions-p)
           (list (make-backup-file-name fn))
         (cons (concat fn ".~" (int-to-string (1+ high-water-mark)) "~")
-              (if (> number-to-delete 0)
+              (if (and (> number-to-delete 0)
+                       ;; Delete nothing if there is overflow
+                       ;; in the number of versions to keep.
+                       (>= (+ kept-new-versions kept-old-versions -1) 0))
                   (mapcar (function (lambda (n)
                                       (concat fn ".~" (int-to-string n) "~")))
                           (let ((v (nthcdr kept-old-versions versions)))