Comment 6 for bug 1457517

My patch just avoid raising FlavorDiskTooSmall error in some ways.

So,the best way is that we don't have to check disk size with flavor if booting from volume.

like this:
        if root_gb and not boot_from_volume: # add a judgment condition
            if int(image.get('size') or 0) > root_gb * (1024 ** 3):
                raise exception.FlavorDiskTooSmall()
            if int(image.get('min_disk') or 0) > root_gb:
                    raise exception.FlavorDiskTooSmall()

is it looks ok?