spam.el not saving spam-stat dictionary

[Chong Yidong <cyd@stupidchicken.com>]

I've been trying to set up the spam-stat spam filtering library, and I
noticed that the new emails I receive aren't being saved into the
spam-stat dictionary.  From what I gather, emails that I mark as spam
are supposed to be "taught" to the dictionary as spam, and the rest of
the email as ham.  In practice, ~/.spam-stat.el hasn't changed since I
first initialized it.


After digging around, I found the follow suspicious code in
`spam-summary-prepare-exit':


	    (dolist (article changed-articles)
	      (let ((id (spam-fetch-field-message-id-fast article)))
		(when (spam-log-unregistration-needed-p
		       id 'process classification check)
		  (push article unregister-list))))
	    (when (and unregister-list (symbol-value check))
	      (spam-register-routine classification check t unregister-list)

The call to spam-register-routine is intended to save the article's
contents to the spam-stat dictionary.

However, in practice unregister-list is always nil, because
spam-log-unregistration-needed-p is defined as

  (defun spam-log-unregistration-needed-p (id type classification check)
    (when spam-log-to-registry
  	....))

And spam-log-to-registry defaults to nil.  Nothing ever gets pushed
onto unregister-list, and spam-register-routine is never called!
Surely this can't be the intended result?