Remove distinct from enterprise.ready_for_checkout scope

Adapt use of enterprise scope not_ready_for_checkout to rails 4 by adding enterprises table alias to selected field id

app/controllers/spree/admin/base_controller_decorator.rb

@@ -53,7 +53,7 @@ def unauthorized
   def active_distributors_not_ready_for_checkout
     ocs = OrderCycle.managed_by(spree_current_user).active
     distributors = ocs.map(&:distributors).flatten.uniq
-    Enterprise.where('id IN (?)', distributors).not_ready_for_checkout
+    Enterprise.where('enterprises.id IN (?)', distributors).not_ready_for_checkout
   end
 
   def active_distributors_not_ready_for_checkout_message(distributors)

app/models/enterprise.rb

@@ -91,15 +91,15 @@ class Enterprise < ActiveRecord::Base
     joins(:shipping_methods).
       joins(:payment_methods).
       merge(Spree::PaymentMethod.available).
-      select('DISTINCT enterprises.id')
+      select('enterprises.id')
   }
   scope :not_ready_for_checkout, lambda {
     # When ready_for_checkout is empty, ActiveRecord generates the SQL:
     # id NOT IN (NULL)
     # I would have expected this to return all rows, but instead it returns none. To
     # work around this, we use the "OR ?=0" clause to return all rows when there are
     # no enterprises ready for checkout.
-    where('id NOT IN (?) OR ?=0',
+    where('enterprises.id NOT IN (?) OR ?=0',
           Enterprise.ready_for_checkout,
           Enterprise.ready_for_checkout.count)
   }