autotest/virt-test — pull request #1543 by xutian (2014-03-26 10:37:25+00:00)
Title: virt.shared.cfg: force cd_format in machines.cfg

force cd_format for unattended_install.cdrom test, because windows guest
not support boot from a virtio_blk or virtio_scsi cdrom.

Signed-off-by: Xu Tian