http://en.wikipedia.org/wiki/User:Kww/fileref is about as simple of a testcase as I could develop. Given this structure:
[[File:Red Wine Glass.jpg|thumb|upright|A "large" (250 ml) glass of 12% ABV red wine has about three units of alcohol. A "medium" (175 ml) glass, such as the one shown, has about two units.<ref> Even though the sizes of wine glasses are defined in UK law, the terms "large", "medium", "standard" etc are not defined in law.</ref>]]
There's no way to edit the reference.