(rmail-convert-mbox-format): Handle mails without subject.

diff --git a/lisp/mail/rmail.el b/lisp/mail/rmail.el
index 3c2c29ec985433fb6b17f75833a3995fe2305aad..1ac64f217cdf1df5d5687b39c946fc415105c140 100644 (file)
--- a/lisp/mail/rmail.el
+++ b/lisp/mail/rmail.el
@@ -1995,8 +1995,9 @@ non-nil then do not show any progress messages."
            ;; Convert encoded-words in from and subject
            (dolist (header '("From" "Subject"))
              (let ((value (rmail-header-get-header header)))
-               (rmail-header-add-header
-                header (mail-decode-encoded-word-string value))))
+               (when value
+                 (rmail-header-add-header
+                  header (mail-decode-encoded-word-string value)))))
            ;; Convert quoted printable transfer encoding because it
            ;; is easy to do.
            (let ((encoding (rmail-header-get-header