autotest/virt-test — pull request #1310 by FengYang (2014-01-03 02:47:22+00:00)
Title: qemu.cfg.qemu_img: Change the way used to limit image_backend variant

"(image_backend=gluster):" is not supported. It is parsed as (image_backend = gluster):

So add "no (image_backend=gluster)" under to_qed variant

Signed-off-by: Feng Yang