Fix a false negative for Rails/TransactionExitStatement

Follow up rubocop#674 (comment)

Revert "[Fix rubocop#669] Fix a false positive for `Rails/TransactionExitStatement`"

This reverts commit d9ec02d and add an example, tweak a spec.

So this PR fixes a false negative for `Rails/TransactionExitStatement` when
`return` is used in `rescue`.

changelog/fix_a_false_negative_for_rails_transaction_exit_statement.md

@@ -0,0 +1 @@
+* [#696](https://github.com/rubocop/rubocop-rails/pull/696): Fix a false negative for `Rails/TransactionExitStatement` when `return` is used in `rescue`. ([@koic][])

lib/rubocop/cop/rails/transaction_exit_statement.rb

@@ -66,7 +66,7 @@ def on_send(node)
           return unless parent.block_type? && parent.body
 
           exit_statements(parent.body).each do |statement_node|
-            next if in_rescue?(statement_node) || nested_block?(statement_node)
+            next if statement_node.break_type? && nested_block?(statement_node)
 
             statement = statement(statement_node)
             message = format(MSG, statement: statement)
@@ -87,13 +87,7 @@ def statement(statement_node)
           end
         end
 
-        def in_rescue?(statement_node)
-          statement_node.ancestors.any? { |n| rescue_body_return_node?(n) }
-        end
-
         def nested_block?(statement_node)
-          return false unless statement_node.break_type?
-
           !statement_node.ancestors.find(&:block_type?).method?(:transaction)
         end
       end

spec/rubocop/cop/rails/transaction_exit_statement_spec.rb

@@ -76,11 +76,12 @@
     RUBY
   end
 
-  it 'does not register an offense when `return` is used in `rescue`' do
-    expect_no_offenses(<<~RUBY)
+  it 'registers an offense when `return` is used in `rescue`' do
+    expect_offense(<<~RUBY)
       ApplicationRecord.transaction do
       rescue
         return do_something
+        ^^^^^^^^^^^^^^^^^^^ Exit statement `return` is not allowed. Use `raise` (rollback) or `next` (commit).
       end
     RUBY
   end