If a foundation is affected by a ranged aura (e.g. the Seleucid hero with -20% enemy building hp as in the replay in #5113) then the completed structure won't be affected by the aura yet so its max hitpoints won't be the same as the foundation's hitpoints, which means with the current code it won't start at full health. Since units are created with hitpoints equal to max hitpoints (except for foundations which have an initial value specified), there's no need to set the hitpoints in Foundation. History at D7352.