Iteration failure on passwd-file when listing all users?

[Marc]

> I'm trying to get a list of all dovecot users, on a simple test setup on
> my local network (which "works", in that I can get IMAP mails from dovecot):
> 
> passdb {
>    driver = passwd-file
>    args = /var/mail/vhosts/%d/shadow
> }
> userdb {
>    driver = passwd-file
>    args = /var/mail/vhosts/%d/passwd
> }
> 
> The command 'doveadm user -u foo at example.com' correctly shows that user.
> However, any attempt to wildcard the user fails:
> 
> # doveadm user -u *@example.com
> Error: auth-master: userdb list: User listing returned failure
> Fatal: user listing failed
> 
> The log file shows
> 
 quotes? shell expands *