Comment 8 for bug 1595096

Fresh install of yakkety which is already sync'd with debian (3.1.0-5)

ubuntu@y1:~$ postmulti -I postfix-example -G postfix -e create config_directory=/etc/postfix-example queue_directory=/var/spool/postfix-example data_directory=/var/lib/postfix-example
postfix/postmulti-script: fatal: Missing main.cf prototype: /etc/postfix/main.cf.proto
ubuntu@y1:~$ dpkg-query -l postfix
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-=============================-===================-===================-================================================================
ii postfix 3.1.0-5 amd64 High-performance mail transport agent

FWIW I built/tested 3..1.0-3.1 for kicks, same error still reported.