Fix BSD slicefix on Linux images
If a Linux image root ext filesystem has the dir_index feature set, the FreeBSD based MFS can corrupt that filesystem. At least for the FreeBSD 9.x implementation of ext2fs. They added an experimental "htree" mechanism to implement this optimization and (according to a later commit that removed the feature) it can corrupt the filesystem "in undetermined circumstances."
I am still figuring out how long this has been a problem, and if it would be a problem with FreeBSD 10.x. It appears to have been exacerbated by my recent changes to slicefix to fix up /etc/ssh/sshd_config and the root authorized_keys file...at least that is what I thought. However, I can make it corrupt just by running sed -i on /etc/fstab and not even changing anything! sed creates a temporary file in /etc and that appears to be enough.