There's something more complicated going on. The ruleset loads fine (one gets to the server prompt). But when I try to load a saved game that uses the same civ2civ3 ruleset, the ruleset loading fails.
During the savegame load, failure flag gets set, causing the load to abort, and that happens with a bogus error message.
That's because loading of research 'free_bulbs' has it's success reversed.
Likely due to --warnings, I get
1: In secfile_lookup_str_vec() [../../../src/utility/registry_ini.c:2247]: secfile '../../src/data/civ2civ3/game.ruleset' in section 'NULL': "goods_good.helptext" entry doesn't exist.
I guess 'helptext' is a mandatory field, but most of the time we get away with it missing?