I'm running a Gnus built fresh from CVS on the Cygwin XEmacs 21.4.20
build. When I send a mail message and attempt to Gcc my "sent mail"
folder on an IMAP server, the outgoing message gets sent, the copy gets
stored in my IMAP folder, but Gnus then reports the following error and
leaves the message composition window open:


Debugger entered--Lisp error: (error "format specifier %d doesn't match argument type")
  format("%d" nil)
  #<compiled-function (item) "...(17)" [item format "%d:%d" "%d"] 4>(nil)
  mapconcat(#<compiled-function (item) "...(17)" [item format "%d:%d" "%d"] 4> (nil) ",")
  imap-range-to-message-set((nil))
  nnimap-request-set-mark("INBOX.sent-mail" (((nil) del (read))) "panix")
  gnus-request-set-mark("nnimap+panix:INBOX.sent-mail" (((nil) del (read))))
  gnus-agent-synchronize-group-flags("nnimap+panix:INBOX.sent-mail" (((nil) del (read))) (nnimap "panix" (nnimap-address "mail.panix.com") (nnimap-stream starttls) (nnimap-need-unselect-to-notice-new-mail t) (nnimap-list-pattern ("INBOX" "INBOX.*"))))
  gnus-agent-regenerate-group("nnimap+panix:INBOX.sent-mail" (nil))
  gnus-request-accept-article("nnimap+panix:INBOX.sent-mail" "nnimap:panix" t t)
  gnus-inews-do-gcc()
  gnus-agent-possibly-do-gcc()
  run-hooks(gnus-agent-possibly-do-gcc)
  message-send(nil)
  message-send-and-exit(nil)
  call-interactively(message-send-and-exit)


I activated imap-log and will include the entire transaction here: