/run/ostree-booted missing after upgrade to 2018.03

[Alex Kiernan <alex kiernan gmail com>]

I've just flipped to 2018.03 (from .02) and I seem to have lost
/run/ostree-booted after that (so everything think's I'm not ostree
booted).

I'm on an embedded board, init is ostree-prepare-root (with no
initramfs) and the main system is then running systemd.

Just staring at what I've got, I'm beginning to wonder if I ever had
/run mounted early enough, or if it just happened to work and I've
never actually had /run/ostree-booted.

Still digging... any pointers gratefully accepted!

-- 
Alex Kiernan