bug 272522 is not fixed in the powerpc autobuilds, i get the same error behaviour mounting /dev/loop0 on /newroot/mnt/livecd failed: Invalid argument Failed to $1 bla bla bla...
*** Bug 277677 has been marked as a duplicate of this bug. ***
CC'ing ranger to make sure he sees it. Ranger, please make sure squashfs-tools is at 4.0 on your build machine.
*** This bug has been marked as a duplicate of bug 275271 ***