Freeciv

An existing building wont fulfill a unit type's impr_req unless the building itself can be built by the player. But the required building may have been build by the city's previous owner or by the current owner before one of its build requirements went away. Example of what this prevents: a ruleset where a unit training building only can be built during peace but can be used to produce units during war.

I think it is too late to change this in 2.6. Is it too late to change this in 3.0 too?