Setting the root password with virt-customize and virt-builder doesn't seem to work with libguestfs-1.27.50. Tested against a virt-builder fedora-20 image.
It worked last week, so I downgraded arbitrarily to libguestfs-1.27.36, tried setting a password, and it worked. yum updated to latest, tried setting a password, and it failed, and the old password didn't work either.
Created attachment 940938 [details]
Output from: sudo virt-customize -v -x --password root:password:1234AA -a fedora-20.img
Something to do with now using Augeas to edit the /etc/shadow file?
(In reply to Richard W.M. Jones from comment #2)
> Something to do with now using Augeas to edit the /etc/shadow file?
Indeed, the way Augeas writes the new file loses the SELinux context. Luckly we have the API for copying attributes.
which are in libguestfs >= 1.27.56.