Rainer Dorsch:
But to my surprise even on a fresh install of the jessie image
/etc/machine-id is already broken:
root@scw-790923:~# cat /etc/machine-id
9d1b906dd5ea40359e2071d29c12aabe
71f
root@scw-790923:~#
But it seems the systemd version in jessie seems to be more tolerant
against broken machine-id fails (?).
It is. Lennart Poettering introduced this intolerance on 2016-07-21.
Before then, /etc/machine-id could contain other stuff after the first
line, and systemd would ignore it because it only ever read and wrote
the 32-character ID and the newline of the first line of the file.
Lennart Poettering changed an I/O function call from an exact length
read of 33 characters to a variable length read of up to 38 characters
followed by a check that the number of characters read is only ever 33,
and the intolerance is as you see now.
So your machine IDs have possibly been like this for a long time.
Your next stops are https://github.com/systemd/systemd/issues/4025 and
https://github.com/scaleway/image-tools/issues/181 .
