Ensure cyclic associations w/ autosave don't cause duplicate errors

This code is so fucked. Things that cause this bug not to replicate:

- Defining the validation before the association (we end up calling
  `uniq!` on the errors in the autosave validation)
- Adding `accepts_nested_attributes_for` (I have no clue why. The only
  thing it does that should affect this is adds `autosave: true` to the
  inverse reflection, and doing that manually doesn't fix this).

This solution is a hack, and I'm almost certain there's a better way to
go about it, but this shouldn't cause a huge hit on validation times,
and is the simplest way to get it done.

Fixes #20874.

1 files changed, 4 insertions, 0 deletions

diff --git a/activerecord/test/schema/schema.rb b/activerecord/test/schema/schema.rb
index 6872b49ad9..2fc806f181 100644
--- a/activerecord/test/schema/schema.rb
+++ b/activerecord/test/schema/schema.rb
@@ -678,6 +678,10 @@ ActiveRecord::Schema.define do
     t.datetime :updated_at
   end
 
+  create_table :prisoners, force: true do |t|
+    t.belongs_to :ship
+  end
+
   create_table :speedometers, force: true, id: false do |t|
     t.string :speedometer_id
     t.string :name