left_join work with join_table raise error

[archfish]

Steps to reproduce

define

create_table :promotions, id: :uuid do |t|
  t.timestamps
end

create_table :products, id: :uuid do |t|
  t.timestamps
end

create_join_table :promotions, :products do |t|
  t.uuid :promotion_id, null:  false
  t.uuid :product_id, null:  false
end

class Promotion < ApplicationRecord
  has_and_belongs_to_many :products, join_table: :products_promotions
end

class Product < ApplicationRecord
  has_and_belongs_to_many :promotions, join_table: :products_promotions
end

use

# this not work
Promotion.left_joins(:products_products).where(products_promotions: {product_id: nil})

# ActiveRecord::ConfigurationError: Can't join 'Promotion' to association named 'products_products'; perhaps you misspelled it?

# this work
Promotion.left_joins(:promotions_products).where(products_promotions: {product_id: nil})

# Promotion Load (0.6ms)  SELECT  "promotions".* FROM "promotions" LEFT OUTER JOIN "products_promotions" ON "products_promotions"."promotion_id" = "promotions"."id" WHERE "products_promotions"."product_id" IS NULL LIMIT $1  [["LIMIT", 11]]

Expected behavior

left_joins should support join_table.

Actual behavior

left_joins raise error with join_table name.

System configuration

Rails version:
Rails 5.2.3

Ruby version:
ruby 2.3.8p459 (2018-10-18 revision 65136) [x86_64-darwin18]

Database version:
postgresql: stable 11.3 (bottled), HEAD