have not yet looked at the syslog but wanted to give an answer right away. First, I think the potentially dangerous layout and your boot not completing are different issues. Whenever the layout becomes an issue I would suspect you would not even get as far as busybox without booting from a rescue system. But I could also be wrong and grub2 maybe has no problems there. But then this should be tracked in a different bug and be used to make the installer aware of this pitfall.
Anyway, for the current problem, we should try to find out why apparently the dmraid activation is not done before trying to mount the rootfs. Thinking about it, maybe it is related to the unusual setup but the old release did handle it correctly, then an upgrade should not break that.
Paul,
have not yet looked at the syslog but wanted to give an answer right away. First, I think the potentially dangerous layout and your boot not completing are different issues. Whenever the layout becomes an issue I would suspect you would not even get as far as busybox without booting from a rescue system. But I could also be wrong and grub2 maybe has no problems there. But then this should be tracked in a different bug and be used to make the installer aware of this pitfall.
Anyway, for the current problem, we should try to find out why apparently the dmraid activation is not done before trying to mount the rootfs. Thinking about it, maybe it is related to the unusual setup but the old release did handle it correctly, then an upgrade should not break that.