ActiveRecord 3.2.6 JOIN issue when models are backed by tables in an alternate database

gistfile1.rb

# In an initializer under config/initializers
[OtherPerson, OtherGroup].each do |model|
  model.establish_connection(other_database[Rails.env].symbolize_keys!)
end

# Model definitions
class OtherGroup < ActiveRecord::Base
  self.table_name = 'groups'
  has_many :other_persons, :class_name => "OtherPerson", :foreign_key => 'group_id'
end

class OtherPerson < ActiveRecord::Base
  self.table_name = 'persons'
  belongs_to :other_group, :foreign_key => 'group_id'

  # This method always returns []
  def self.find_eligible_people(group)
    person_relation = OtherPerson.scoped.
      where(:status => "happy").
      joins(:other_group).
      where(:groups => {:name => group.name})

    person_relation
  end

  # The workaround
  def self.find_eligible_people(group)
    group_id = OtherGroup.where(:name => group.name).first.id
    person_relation = OtherPerson.scoped.
      where(:status => "happy").
      where(:group_id => group_id)

    person_relation
  end
end