Comment # 55 on bug 937237 from Thomas Blume

(In reply to Steffen Winterfeldt from comment #54)
> Ok, rescue is now its own file system and the systemd error is gone.
> 
> HOWEVER, it now mounts the root-fs ro. Any idea why and how to stop this?

I assume that the rescue system doesn't have an fstab entry for system root
mount.
If so, systemd-fstab-generator would fail to remount system root rw after the
initrd.
You could try with the boot parameters:

rw 

and/or:

rootflags=rw