I've just updated my dovecot on centos, after 'yum update' dovecot failed to work, with manual restart it worked fine, just giving a warning:

# dovecot Warning: Corrected permissions for login directory /var/run/dovecot/token-login

dovecot --version 2.3.7.2 (3c910f64b)

all's good, just reporting in case this is relevant to rpm maintainers

thanks, V