Merge pull request #12791 from jasonayre/ja/fix_autoload_error

add autoload :TransactionState to fix Marshal.load issues

activerecord/CHANGELOG.md

+*   Fix uninitialized constant TransactionState error when Marshall.load is used on an Active Record result.
+    Fixes #12790
+
+    *Jason Ayre*
+
 *   `.unscope` now removes conditions specified in `default_scope`.
 
     *Jon Leighton*

activerecord/lib/active_record/connection_adapters/abstract_adapter.rb

@@ -40,6 +40,7 @@ module ConnectionAdapters # :nodoc:
       autoload :ClosedTransaction
       autoload :RealTransaction
       autoload :SavepointTransaction
+      autoload :TransactionState
     end
 
     # Active Record supports multiple database systems. AbstractAdapter and