I updated to

commit 14b8787ecb5038a1bdfdd060a32afbabd1582918
Author: Julien Danjou <julien@danjou.info>
Date:   Wed Jul 25 14:01:11 2012 +0200

    Restore `gnus-kill-sticky-article-buffers'
    
    Signed-off-by: Julien Danjou <julien@danjou.info>

from

commit ca6a7cad961ef39b97fad1d06007246df5dbe47a
Author: Julien Danjou <julien@danjou.info>
Date:   Tue Jun 19 14:47:26 2012 +0200

    nnimap: fix window-point-insertion-type for XEmacs
    
    Signed-off-by: Julien Danjou <julien@danjou.info>


and got:

  message-get-reply-headers: Autoloading failed to define function mail-dont-reply-to

when typing 'r' to a message in nnimap summary.