[CentOS] Systemd debug logging turned on in CentOS 7

Hi,

I noticed that some, but not all, of my CentOS 7 machines have these
kernel parameters for turning on systemd debug level logging added to
the grub.cfg file.

  systemd.log_level=debug systemd.log_target=kmsg

The parameters are *not* in the /etc/default/grub file, so if I rebuild
grub.cfg with grub2-mkconfig, they disappear.

I am a bit puzzled over how they got introduced.
Has anyone else seen this?

thanks,

	Thomas