dovecot - Oct 2017 - How to require client SSL certificate, except for local connections

Is there any way to make Dovecot 2.2.22 not require a client SSL 
certificate for a local IMAP connection, but require it for any remote 
IMAP connection?

My server is configured to require client certificates:

ssl = required
...
auth_ssl_require_client_cert = yes

I tried adding the following to create an exception for localhost:

remote 127.0.0.1 {
 ? ssl = no
 ? auth_ssl_require_client_cert = no
 ? disable_plaintext_auth = no
}

But Dovecot fails to start with: doveconf: Fatal: Error in configuration 
file /etc/dovecot/dovecot.conf line 81: Auth settings not supported 
inside local/remote blocks:

Is there any other way to do this? I don't need to override any other 
auth settings, just that one. I could probably use a Unix socket, if 
that would help.

Thanks,

Evan