Why dpreview switched from 50/1.4 to 50/1.8 in latest Sony tests

I wonder why latest Sony SLT bodies (like A77) are tested using Sony SAL-50F18 (at least this is what I can tell from EXIF)?

For instance, if I check the very upper left corner of the Dpreview's Studio Scene test image for A57 and A580, resolution on A580 seems to be higher. A580 was tested with 50/1.4 according to EXIF.