Comment 3 for bug 1441990

@ftersin:
Yes, In master branch, novaclient has supported to boot vm with bdm args that boot_index=1. But in nova side , this issue still exist if not using novaclient to boot vm. Now it need user to add duplicate bdm args like 'source=image, dest=local, boot_index=0', although user has specified 'image_ref' arg to boot vm. So this patch want to make it easy when boot vm from image and with bdm args.