(mail-mode): Make adaptive-fill-regexp

match more values.  Bind adaptive-fill-first-line-regexp too.

lisp/mail/sendmail.el

@@ -348,7 +348,9 @@ C-c C-v  mail-sent-via (add a Sent-via field for each To or CC)."
   (setq fill-paragraph-function 'mail-mode-fill-paragraph)
   (make-local-variable 'adaptive-fill-regexp)
   (setq adaptive-fill-regexp
-	(concat "[ \t]+[a-z0-9A-Z]+> *\\|" adaptive-fill-regexp))
+	(concat "[ \t]+[a-z0-9A-Z]*>+ *\\|" adaptive-fill-regexp))
+  (make-local-variable 'adaptive-fill-first-line-regexp)
+  (setq adaptive-fill-first-line-regexp adaptive-fill-regexp)
   ;; `-- ' precedes the signature.  `-----' appears at the start of the
   ;; lines that delimit forwarded messages.
   ;; Lines containing just >= 3 dashes, perhaps after whitespace,