Fix `cache_key` with a relation having custom select and order

We can't replace existing select list as long as referenced by ORDER BY.

activerecord/lib/active_record/collection_cache_key.rb

@@ -20,8 +20,7 @@ module ActiveRecord
         select_values = "COUNT(*) AS #{connection.quote_column_name("size")}, MAX(%s) AS timestamp"
 
         if collection.has_limit_or_offset?
-          query = collection.spawn
-          query.select_values = [column]
+          query = collection.select(column)
           subquery_alias = "subquery_for_cache_key"
           subquery_column = "#{subquery_alias}.#{timestamp_column}"
           subquery = query.arel.as(subquery_alias)

activerecord/test/cases/collection_cache_key_test.rb

@@ -141,5 +141,11 @@ module ActiveRecord
 
       assert_match(/\Adevelopers\/query-(\h+)-(\d+)-(\d+)\z/, developers.cache_key)
     end
+
+    test "cache_key with a relation having custom select and order" do
+      developers = Developer.select("name AS dev_name").order("dev_name DESC").limit(5)
+
+      assert_match(/\Adevelopers\/query-(\h+)-(\d+)-(\d+)\z/, developers.cache_key)
+    end
   end
 end