Extending the Gnus pyzor example

[Christopher Culver]

In the Gnus manual, there is a helpful example of how to report spam
using Pyzor:

(defun my-gnus-raze-spam ()
       "Submit SPAM to Vipul's Razor, then mark it as expirable."
       (interactive)
       (gnus-summary-save-in-pipe "razor-report -f -d" t)
       (gnus-summary-mark-as-expirable 1))

Now, I'd like to change this so that it first moves mail to another
group ("nnml:spam"), and *then* marks it expirable. But once mail has
been moved to another group, how can I access it to mark it as
expirable?

If I try setting it as expirable with gnus-summary-mark-as-expirable
first and then moving it, I get unintended results. The move function
actually ends up moving the next e-mail in the group since setting mail
as expirable automatically selects the next message.

(I have a cron job that runs Spamassassin's Bayesian trainer on my inbox
as ham and the nnml:spam group as spam, that's why I cannot leave spam
messages within my inbox.)