no need for Array.wrap

activerecord/lib/active_record/relation/predicate_builder.rb

@@ -19,7 +19,7 @@ def self.build_from_hash(engine, attributes, default_table)
 
           case value
           when ActiveRecord::Relation
-            value.select_values = Array.wrap("#{value.klass.quoted_table_name}.id") if value.select_values.empty?
+            value.select_values = ["#{value.klass.quoted_table_name}.id"] if value.select_values.empty?
             attribute.in(value.arel.ast)
           when Array, ActiveRecord::Associations::AssociationCollection
             values = value.to_a.map { |x|