Improve test setup
Improve test setup

This enables custom heroes with prepare_empty_game.

amw2104/fireplace,Ragowit/fireplace,NightKev/fireplace,liujimj/fireplace,smallnamespace/fireplace,oftc-ftw/fireplace,liujimj/fireplace,Meerkov/fireplace,oftc-ftw/fireplace,amw2104/fireplace,Meerkov/fireplace,Ragowit/fireplace,jleclanche/fireplace,smallnamespace/fireplace,beheh/fireplace