Confusing iterator behavior in copy: section

[Chip Seraphine]

I'd like to be able to copy a list of files into my postfix jail, like this:

control:
     postfix_host::
              postfix_jailfiles=      (
                
"hosts:localtime:nsswitch.conf:resolv.conf:services:host.conf" )

copy:
       postfix_host::
              /etc/$(postfix_jailfiles)
                      dest=/var/spool/postfix/etc/
                       type=mtime




...but what I get an error telling me the destination type is silly (as 
/var/spool/postfix/etc).   If I try phrasing the copy directive thusly:

copy:
       postfix_host::
              /etc/$(postfix_jailfiles)
                      dest=/var/spool/postfix/etc/$(postfix_jailfiles)
                       type=mtime

...then I end up with a single file (containing /etc/hosts content) 
named 
"/var/spool/postfix/etc/hosts:localtime:nsswitch.conf:resolv.conf:services:host.conf".

I have simply changed to a series of explicit copies, but this behavior 
has caused me to wonder if there is any use at all for having iterators 
in the copy: action.

How are other people dealing with this?