Fix `stale_state` for nested `has_many :through` associations

Need reloading when through record has replaced.

2 files changed, 13 insertions, 10 deletions

diff --git a/activerecord/lib/active_record/associations/through_association.rb b/activerecord/lib/active_record/associations/through_association.rb
index 806397f83a..54673b74f7 100644
--- a/activerecord/lib/active_record/associations/through_association.rb
+++ b/activerecord/lib/active_record/associations/through_association.rb
@@ -4,9 +4,20 @@ module ActiveRecord
   module Associations
     # = Active Record Through Association
     module ThroughAssociation #:nodoc:
-      delegate :source_reflection, :through_reflection, to: :reflection
+      delegate :source_reflection, to: :reflection
 
       private
+        def through_reflection
+          @through_reflection ||= begin
+            refl = reflection.through_reflection
+
+            while refl.through_reflection?
+              refl = refl.through_reflection
+            end
+
+            refl
+          end
+        end
 
         # We merge in these scopes for two reasons:
         #
@@ -68,7 +79,7 @@ module ActiveRecord
         end
 
         def foreign_key_present?
-          through_reflection.belongs_to_or_through? && !owner[through_reflection.foreign_key].nil?
+          through_reflection.belongs_to? && !owner[through_reflection.foreign_key].nil?
         end
 
         def ensure_mutable
diff --git a/activerecord/lib/active_record/reflection.rb b/activerecord/lib/active_record/reflection.rb
index 7b53f9c15c..9e32b69786 100644
--- a/activerecord/lib/active_record/reflection.rb
+++ b/activerecord/lib/active_record/reflection.rb
@@ -504,10 +504,6 @@ module ActiveRecord
         @association_scope_cache.clear
       end
 
-      def belongs_to_or_through?
-        belongs_to?
-      end
-
       def nested?
         false
       end
@@ -840,10 +836,6 @@ module ActiveRecord
         source_reflection.join_scopes(table, predicate_builder) + super
       end
 
-      def belongs_to_or_through?
-        through_reflection.belongs_to_or_through?
-      end
-
       def has_scope?
         scope || options[:source_type] ||
           source_reflection.has_scope? ||