Even with https://bugzilla.redhat.com/show_bug.cgi?id=1285903 fixed, Rawhide nightly boot.iso's fail to boot, and this is still dracut's fault. I think I know what got broken.

If you boot a 2015-11-30 Rawhide nightly boot.iso , it fails to boot because /dev/root doesn't exist. In fact, /dev/root is a symlink to /dev/mapper/live-rw, which doesn't exist. On a working image (2015-11-12 is what I'm comparing with), /dev/mapper/live-rw is a symlink to /dev/dm-0 , which exists.

There is also an interesting error: "umount: /run/initramfs/squashfs: mountpoint not found"

What I think is going on is actually pretty simple: the changes in dracut 044 have made it so dmsquash-live-root.sh no longer sets up the squashfs for anaconda images properly. Specifically, this commit:

https://git.kernel.org/cgit/boot/dracut/dracut.git/commit?id=8b5ee88ff667693b2d8da85a8552ad8f5ab95127

more specifically, the very first change in that commit. It makes it so this block:

    SQUASHED_LOOPDEV=$( losetup -f )
    losetup -r $SQUASHED_LOOPDEV $SQUASHED
    mkdir -m 0755 -p /run/initramfs/squashfs
    mount -n -t squashfs -o ro $SQUASHED_LOOPDEV /run/initramfs/squashfs

only happens "if [ -e /run/initramfs/live/${live_dir}/${squash_image} ]". Previously, it happened "if [ -e "$SQUASHED" ]". Frederick Grose was, I think, assuming that $SQUASHED only gets set in that block anyway, but that is incorrect. It can also be set earlier in dmsquash-live-root.sh:

if [ -f $livedev ]; then
    # no mount needed - we've already got the LiveOS image in initramfs
    # check filesystem type and handle accordingly
    fstype=$(det_img_fs $livedev)
    case $fstype in
        squashfs) SQUASHED=$livedev;;

and that, I believe, is the case we hit with an anaconda boot. So in this case, the block of code that's intended to mount /run/initramfs/squashfs - from where an FSIMG will be found, and set up as /dev/mapper/live-rw - never gets run, so we never get an FSIMG and we never get a /dev/mapper/live-rw.