zlib plugin doesn't add "Z" flag to Maildir filename

[Tom Sommer]

I enabled zlib compression, so new mails are saved compressed.

Now I want to convert the old mails to gzip with the find and gzip 
command, but now I don't know which files are already gzip compressed by 
dovecot.

Shouldn't zlib_save itself add Z to the Maildir flags? As suggested in 
the compress guide on http://wiki2.dovecot.org/Plugins/Zlib ?

-- 
Tom