(gnus-permanently-visible-groups): Fix customize type.

diff --git a/lisp/gnus/gnus-group.el b/lisp/gnus/gnus-group.el
index eec47aaa06e7ceafcdd320f8541bc0a0c3ce99bb..521fd21d0ddaf3fd5ed53d0418ecda68d4176855 100644 (file)
--- a/lisp/gnus/gnus-group.el
+++ b/lisp/gnus/gnus-group.el
@@ -87,7 +87,7 @@ with the best level."
 This means that they will still be listed when there are no unread
 articles in the groups."
   :group 'gnus-group-listing
-  :type 'regexp)
+  :type '(choice regexp (const nil)))
 
 (defcustom gnus-list-groups-with-ticked-articles t
   "*If non-nil, list groups that have only ticked articles.