It looks like it comes from here https://github.com/rails/rails/blob/v3.0.20/activerecord/lib/active_record/base.rb#L859-L867 but with connection_pool_name instead of name.

It's copy-paste from https://github.com/zendesk/active_record_shards/blob/master/lib/active_record_shards/connection_pool.rb#L43-L56.