Dovecot 2.3.17 can not start - too many parameters. but the same config is working on 2.3.16 (and for a long time already ...)

started via systemd unit file :
==================
[Unit]
Description=Dovecot IMAP/POP3 email server
Documentation=man:dovecot(1)
Documentation=http://wiki2.dovecot.org/
After=local-fs.target network.target dnsmasq.service NetworkManager-wait-online.service network-online.target
Requires=network.target network-online.target dnsmasq.service local-fs.target
[Service]
Type=forking
ExecStart=/usr/local/sbin/dovecot -c /etc/dovecot/dovecot.conf
PIDFile=/usr/local/var/run/dovecot/master.pid
ExecReload=/usr/local/bin/doveadm reload
ExecStop=/usr/local/bin/doveadm stop
PrivateTmp=true
NonBlocking=yes
LimitNOFILE=8192
[Install]
WantedBy=multi-user.target
==================

log:
Oct 29 18:48:58 lxc-imap dovecot[1781]: doveconf: Fatal: execvp(/usr/local/sbin/dovecot) failed: Argument list too long
Oct 29 18:48:58 lxc-imap systemd[1]: dovecot.service: Control process exited, code=exited, status=89/n/a
Oct 29 18:48:58 lxc-imap systemd[1]: dovecot.service: Failed with result 'exit-code'.

but when I run doveconf -n, it is working under 2.3.17
I needed to revert to version 2.3.16 to send this email ;-)

running on Ubuntu impish

yours sincerely

Robert Nowotny
Rotek GmbH