With libexiv2 0.27.3, "charset=Ascii" appears before the comment of the image
With gthumb 3.8.3 and libexiv2 0.27.3 (not with previous versions of libexiv2), charset=Ascii
appears before the comment of the image. This is due to the following change in exiv2: https://github.com/Exiv2/exiv2/issues/1258