[Exim] acl_xx in system filter

Hi!

Are $acl_xx vars accessible in the system filter?
My tests shows that they are not, but in ChangeLog for 4.22 I see:

40. The ACL variables $acl_xx are now saved with the message, and can be
    accessed later in routers, transports, and filters.

Now I add header line in the acl_smtp_data and get it in
the system filter, but it's less comfortable then use
acl_xx variables.

Is it a bug or feature? Or I do somthing wrong in my tests?

P.S. Does it planning to add "set" command to filter? ;-)

--
                                Lucky carrier,
                                                  Pavel.