(frame-delete-all): Copy the whole alist first.

diff --git a/lisp/frame.el b/lisp/frame.el
index 0688b3098d5ae2adce04f6f3a1e6ec60e544ef01..b529afc89813bf1fc8f521c394a87246207102dc 100644 (file)
--- a/lisp/frame.el
+++ b/lisp/frame.el
@@ -336,6 +336,7 @@ These supersede the values given in `default-frame-alist'.")
 ;; Delete from ALIST all elements whose car is KEY.
 ;; Return the modified alist.
 (defun frame-delete-all (key alist)
+  (setq alist (copy-sequence alist))
   (let ((tail alist))
     (while tail
       (if (eq (car (car tail)) key)