Great researching abilities! Thanks for the link. How was this not a test though?
B/c it wasn't officially declared a Test match. The '49 Tour to SA had four Test matches; Rhodesia was none of them. (They played Rhodesia twice.) (Worst AB tour ever.) (British Lions used to regularly play Rhodesia on their SA tours as well, and those were not test matches either.)
I think Rhodesia was in the Currie Cup B competition so these were just touring matched and Rhodesian players were available for the Springboks during that era..