An exhaustive search of options.json finds only these entries missing from default.cfg:
"config": "playername.singleplayer" "config": "playername.multiplayer" "config": "gui.session.ceasefirecounter" "config": "watershadows",
gui.session.ceasefirecounter was missing from rP16624.
watershadows should've been changed to shadowsonwater in rP15473.