As pointed out by @Genava55 [[ https://wildfiregames.com/forum/index.php?/topic/25184-task-current-issues-with-celtic-units-and-guideline-for-the-next/page/7/&tab=comments#comment-393215 | on the forums ]], 0 A.D.'s rotary mill is historically problematic. This patch therefore deprecates the structure, and instead introduces a special technology (town phase, workers +10% grain gather rate) for the Gauls, to reflect the fact they invented a harvesting machine in the Iron Age.
See also D2669.