Error when resending previously resent email

[David desJardins]

Currently, when using rmail-resend, the behavior is incorrect when the
message has previously been resent.  That's because the
previously-resent message has Resent-To fields, and these are not
removed, so the message is sent again to the previous recipients.

This patch corrects this behavior, by stripping existing Resent-*:
header lines when resending a message.

  -- David desJardins

*** rmail.el    Tue Jul 31 16:00:50 2001
--- lisp/rmail.el       Thu Feb 22 10:49:38 2001
***************
*** 2902,2908 ****
          (re-search-forward "^$" nil 'move)
          ; Using "while" here rather than "if" because some buggy mail
          ; software may have inserted multiple Sender fields.
!         (while (re-search-backward "^Sender:" nil t)
            (let (beg)
              (setq beg (point))
              (forward-line 1)
--- 2902,2908 ----
          (re-search-forward "^$" nil 'move)
          ; Using "while" here rather than "if" because some buggy mail
          ; software may have inserted multiple Sender fields.
!         (while (re-search-backward "^Sender:\\|^Resent-" nil t)
            (let (beg)
              (setq beg (point))
              (forward-line 1)
***************