Starting our services on Ubuntu systems (and Debian?) gives the following log line:
> Oct 19 00:06:20 ubuntu1804 bash: mesg: ttyname failed: Inappropriate ioctl for device
This is caused by us starting our services through a login shell (for locale, see bug 5102) and Ubuntu has this in ~root/.profile:
> mesg n || true
(Note that this is only seen in "systemctl status" as it happens before we set up our own logging)
Tested on Ubuntu 18.04.