Mirror lenses have a center obstruction, where the secondary mirror is located. So, out-of-focus points of light become donut-shaped blurs. The only mirror lenses I've seen are long focal length. Your photo sort of looks like it could be from a mirror lens, but the intensity of the blur is so concentrated on the very outside edge of the bokeh, that I'm wondering if the effect might have been caused by a sharpening algorithm applied to the image.
