autotest/virt-test — pull request #780 by ldoktor (2013-08-26 17:11:52+00:00)
Title: virttest.qemu_devices: Add default value to drive_format

Apperently drive_format doesn't have to be defined. Add default
value 'virtio_blk' to avoid using .startswith on a None object.

Signed-off-by: Lukáš Doktor