gnus-summary-mark-as-spam won't move spam articles from an IMAP group

[Julien Cubizolles]

I just noticed that articles manually marked as spam
(gnus-summary-mark-as-spam) in the Summary buffer for an IMAP group
aren't moved to the spam-split-group like they used to, they are just
flagged as expirable. 

However spam articles flagged by bogofilter when splitting are still
moved to this spam-split-group.

Is there something obviously wrong in my setup ? It used to work until a
few weeks ago.

--8<---------------cut here---------------start------------->8---
(setq spam-use-bogofilter t)

(require 'spam)

(spam-initialize 'spam-use-move)

(setq spam-log-to-registry t)
(setq spam-mark-ham-unread-before-move-from-spam-group t)
(setq spam-mark-only-unseen-as-spam t)
;; (setq spam-autodetect-recheck-messages t)

(setq spam-split-group "Junk")

--8<---------------cut here---------------end--------------->8---