Comment 1 for bug 1414251

This fixes it for me on amd64 and I can log in on console in the end

Would need testing in other configurations like arm etc.

=== modified file 'scripts/ubuntu-core-rootfs'
--- scripts/ubuntu-core-rootfs 2015-01-21 08:29:21 +0000
+++ scripts/ubuntu-core-rootfs 2015-01-24 01:57:08 +0000
@@ -159,6 +159,9 @@
  [ "$quiet" != "y" ] && log_end_msg

  # Make sure the device has been created by udev before we try to mount
+ wait-for-root /dev/disk/by-label/system-a 180
+ wait-for-root /dev/disk/by-label/system-b 180
+ udevadm trigger
  udevadm settle

  # There are 2 root partitions but grub tells us which to boot