Ensure we can nest include calls [#5285 state:resolved]

Signed-off-by: José Valim <jose.valim@gmail.com>

2 files changed, 8 insertions, 2 deletions

diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
index cd6c6f8d1f..0bf0b37900 100644
--- a/activerecord/lib/active_record/relation/query_methods.rb
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -11,7 +11,7 @@ module ActiveRecord
 
     def includes(*args)
       args.reject! { |a| a.blank? }
-      clone.tap {|r| r.includes_values += args if args.present? }
+      clone.tap {|r| r.includes_values = (r.includes_values + args).flatten.uniq if args.present? }
     end
 
     def eager_load(*args)
diff --git a/activerecord/lib/active_record/relation/spawn_methods.rb b/activerecord/lib/active_record/relation/spawn_methods.rb
index 02db8d2b89..f857e50dea 100644
--- a/activerecord/lib/active_record/relation/spawn_methods.rb
+++ b/activerecord/lib/active_record/relation/spawn_methods.rb
@@ -8,7 +8,13 @@ module ActiveRecord
 
       ((Relation::ASSOCIATION_METHODS + Relation::MULTI_VALUE_METHODS) - [:joins, :where]).each do |method|
         value = r.send(:"#{method}_values")
-        merged_relation.send(:"#{method}_values=", value) if value.present?
+        if value.present?
+          if method == :includes
+            merged_relation = merged_relation.includes(value)
+          else
+            merged_relation.send(:"#{method}_values=", value) 
+          end
+        end
       end
 
       merged_relation = merged_relation.joins(r.joins_values)