It sorta looks like Rails fixtures can't handle joiner tables that have t.timestamps on them

1-20180123123916_create_posts_tags.rb

class CreatePostsTags < ActiveRecord::Migration[5.1]
  def change
    create_table :posts_tags do |t|
      t.references :post, foreign_key: true
      t.references :tag, foreign_key: true

      t.timestamps
    end
  end
end

2-tags.yml

hills:
  name: hills
  author: jack

pails:
  name: pails
  author: jill

water:
  name: water
  author: jack

crown:
  name: crown
  author: jill

tumbling:
  name: tumbling
  author: jack

3-posts.yml

caution:
  title: Avoid the hill!
  body: Turns out, it's really easy to fall down the hill and break your crown
  author: jack
  tags: hills, crown, tumbling

plumbing:
  title: We need water supply
  body: It's ridiculous we're still fetching water with a pail, we need plumbing
  author: jill
  tags: water, pails

4-failure.txt

$ rake db:drop db:setup db:fixtures:load
Dropped database 'simple-example_development'
Dropped database 'simple-example_test'
Created database 'simple-example_development'
Created database 'simple-example_test'
-- enable_extension("plpgsql")
   -> 0.0203s
-- create_table("authors", {:force=>:cascade})
   -> 0.0063s
-- create_table("posts", {:force=>:cascade})
   -> 0.0098s
-- create_table("posts_tags", {:force=>:cascade})
   -> 0.0083s
-- create_table("tags", {:force=>:cascade})
   -> 0.0062s
-- add_foreign_key("posts", "authors")
   -> 0.0049s
-- add_foreign_key("posts_tags", "posts")
   -> 0.0021s
-- add_foreign_key("posts_tags", "tags")
   -> 0.0025s
-- add_foreign_key("tags", "authors")
   -> 0.0014s
-- enable_extension("plpgsql")
   -> 0.0229s
-- create_table("authors", {:force=>:cascade})
   -> 0.0050s
-- create_table("posts", {:force=>:cascade})
   -> 0.0088s
-- create_table("posts_tags", {:force=>:cascade})
   -> 0.0097s
-- create_table("tags", {:force=>:cascade})
   -> 0.0076s
-- add_foreign_key("posts", "authors")
   -> 0.0030s
-- add_foreign_key("posts_tags", "posts")
   -> 0.0018s
-- add_foreign_key("posts_tags", "tags")
   -> 0.0017s
-- add_foreign_key("tags", "authors")
   -> 0.0013s
rake aborted!
ActiveRecord::NotNullViolation: PG::NotNullViolation: ERROR:  null value in column "created_at" violates not-null constraint
DETAIL:  Failing row contains (1, 1050461717, 684148082, null, null).
: INSERT INTO "posts_tags" ("post_id", "tag_id") VALUES (1050461717, 684148082)


Caused by:
PG::NotNullViolation: ERROR:  null value in column "created_at" violates not-null constraint
DETAIL:  Failing row contains (1, 1050461717, 684148082, null, null).

Tasks: TOP => db:fixtures:load
(See full trace by running task with --trace)