#4566: Remove extra decrement of transaction level

`rollback_active_record_state!` tries to restore model state on `Exception`
by invoking `restore_transaction_record_state` it decrement deep level by `1`.

After restoring it ensure that states to be cleared
and level decremented by invoking `clear_transaction_record_state`,
which cause the bug: because state already reduced in `restore_transaction_record_state`.

Removed double derement of transaction level
and removed duplicated code which clear transaction state for top level.

3 files changed, 23 insertions, 3 deletions

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 404443f4ad..624c26e759 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,9 @@
+*   Remove extra decrement of transaction deep level.
+
+    Fixes: #4566
+
+    *Paul Nikitochkin*
+
 *   Reset @column_defaults when assigning `locking_column`.
     We had a potential problem. For example:
 
diff --git a/activerecord/lib/active_record/transactions.rb b/activerecord/lib/active_record/transactions.rb
index 62920d936f..dcbf38a89f 100644
--- a/activerecord/lib/active_record/transactions.rb
+++ b/activerecord/lib/active_record/transactions.rb
@@ -304,6 +304,7 @@ module ActiveRecord
       run_callbacks :rollback
     ensure
       restore_transaction_record_state(force_restore_state)
+      clear_transaction_record_state
     end
 
     # Add the record to the current transaction so that the +after_rollback+ and +after_commit+ callbacks
@@ -360,8 +361,8 @@ module ActiveRecord
     # Restore the new record state and id of a record that was previously saved by a call to save_record_state.
     def restore_transaction_record_state(force = false) #:nodoc:
       unless @_start_transaction_state.empty?
-        @_start_transaction_state[:level] = (@_start_transaction_state[:level] || 0) - 1
-        if @_start_transaction_state[:level] < 1 || force
+        transaction_level = (@_start_transaction_state[:level] || 0) - 1
+        if transaction_level < 1 || force
           restore_state = @_start_transaction_state
           was_frozen = restore_state[:frozen?]
           @attributes = @attributes.dup if @attributes.frozen?
@@ -374,7 +375,6 @@ module ActiveRecord
             @attributes_cache.delete(self.class.primary_key)
           end
           @attributes.freeze if was_frozen
-          @_start_transaction_state.clear
         end
       end
     end
diff --git a/activerecord/test/cases/transactions_test.rb b/activerecord/test/cases/transactions_test.rb
index c0cad52b22..9c5f2e4724 100644
--- a/activerecord/test/cases/transactions_test.rb
+++ b/activerecord/test/cases/transactions_test.rb
@@ -117,6 +117,20 @@ class TransactionTest < ActiveRecord::TestCase
     assert !Topic.find(1).approved?
   end
 
+  def test_raising_exception_in_nested_transaction_restore_state_in_save
+    topic = Topic.new
+
+    def topic.after_save_for_transaction
+      raise 'Make the transaction rollback'
+    end
+
+    assert_raises(RuntimeError) do
+      Topic.transaction { topic.save }
+    end
+
+    assert topic.new_record?, "#{topic.inspect} should be new record"
+  end
+
   def test_update_should_rollback_on_failure
     author = Author.find(1)
     posts_count = author.posts.size