conditions_tables doesn't understand :condition hashes

Finder methods fail when:

(1) there is a :limit, and
(2) there are :includes, and
(3) the conditions clause is a hash, and
(4) the conditions reference the :included association.

For example, the following query fails:

Widget.find :all,

 :conditions => {"users.state" => "active", "tags.name" => "fun"},
 :include => [:creator, :tags],
 :limit => 20

Mysql::Error: Unknown column 'users.state' in 'where clause': SELECT DISTINCT widgets.id FROM widgets WHERE (users.state = 'active' AND tags.name = 'new') LIMIT 20

The problem is in ActiveRecord::Associations::ClassMethods::conditions_tables, associations.rb, line 1513ff:

    def conditions_tables(options)
      # look in both sets of conditions
      conditions = [scope(:find, :conditions), options[:conditions]].inject([]) do |all, cond|
        case cond
          when nil   then all
          when Array then all << cond.first
          else            all << cond
        end
      end
      conditions.join(' ').scan(/([\.a-zA-Z_]+).?\./).flatten
    end

The case statement is failing for hashes. It needs an extra "when" to handle them:

          when Hash  then all << cond.keys

Here is the patch in context:

    def conditions_tables(options)
      # look in both sets of conditions
      conditions = [scope(:find, :conditions), options[:conditions]].inject([]) do |all, cond|
        case cond
          when nil   then all
          when Array then all << cond.first
          when Hash  then all << cond.keys  # <--- PATCH
          else            all << cond
        end
      end
      conditions.join(' ').scan(/([\.a-zA-Z_]+).?\./).flatten
    end