Using colas to baste/glaze a ham was fairly common, at least here in the South, during WW II due to sugar rationing. It appears that while sugar was rationed and in limited supply (brown sugar was extremely hard to get) - colas were not rationed and were usually readily available, especially in the areas within about 100 miles of a bottling plant. There were other interesting inventions during this time like the Coca-Cola Cake, some qiuick breads, cola glazed pork chops, to make BBQ sauce, etc.
Other colas commonly used to glaze hams were Dr. Pepper for it's fruity "prune" flavor and Root Beer for it's sassafras flavoring.
"It ain't what you don't know that gets you in trouble. It's what you know for sure that just ain't so." - Mark Twain