Stopped the client. Removed _contents_ of /var/lib/puppet/ssl.
[root@puppettest puppet]# puppetd --test
info: Creating a new certificate request for puppettest.domain.com
info: Creating a new SSL key at /var/lib/puppet/ssl/private_keys/puppettest.domain.com.pem
warning: peer certificate won't be verified in this SSL session
notice: Did not receive certificate
notice: Set to run 'one time'; exiting with no certificate