`make-full-mail-header' to "nobody" instead of "".
(let ((gnus-summary-line-format-spec spec)
(gnus-newsgroup-downloadable '((0 . t))))
(gnus-summary-insert-line
- (make-full-mail-header 0 "" "" "" "" "" 0 0 "" nil)
+ (make-full-mail-header 0 "" "nobody" "" "" "" 0 0 "" nil)
0 nil 128 t nil "" nil 1)
(goto-char (point-min))
(setq pos (list (cons 'unread (and (search-forward "\200" nil t)