When connection should get from model through :model attribute, load_config loaded and set connection_hash. After that for connection_class instead of using model value it use connection_hash. All this two cases are bugs. I added fix changes to pull request:
Model has more priority over connection_hash
* Skip load_config for ActiveRecord if model set for strategy.
* If model and connection_hash are set, then should return model as connection_class instead of connection_hash builder
Makes sense, and the patch looks good (travis build is in disrepair so you can ignore that). Merged in, thanks.