Context manager decorator never runs __exit__ if setUp fails inside test

Question

I'm trying to solve a bug in django. The bug involves a class called TextContextDecorator which can be used a class decorator and/or context manager.

As the bug description mentions, when using TextContextDecorator as class decorator enable is called just before Test.setUp, and disable is called after Test.tearDown.unfortunately, tearDown is not called in the event of a failure inside setUp. This can result in unexpected behaviour.

One of the proposed solutions is that to use addCleanUp inside the setUp of TestContextDecorator, but I'm having difficulties in calling that function inside of decorator class.

Here is the sample code provided to reproduce the bug..

class example_decorator(TestContextDecorator):
    some_var = False

    def enable(self):
        self.__class__.some_var = True

    def disable(self):
        self.__class__.some_var = False

class Example1TestCase(TestCase):
    def test_var_is_false(self):
        # some_var will be False
        self.assertFalse(example_decorator.some_var)


@example_decorator()
class Example2TestCase(TestCase):
    def setUp(self):
        raise Exception

    def test_var_is_true(self):
        # won't be hit due to exception in setUp
        self.assertTrue(example_decorator.some_var)


class Example3TestCase(TestCase):
    def test_var_is_false(self):
        # some_var will be True now due to no cleanup in Example2TestCase
        self.assertFalse(example_decorator.some_var)

So far i have used try and except inside the setUp of TestContextDecorator and that seems to solve the bug but i'm not sure if its the best way to do it. Here are the changes i made (i have added try and except on line 30 of code provided in the link).

Question: What would be the correct way to run a function similar to tearDown in the event of failure inside setUp of Test when in a context manager? Is the try and except method that i used correct? or can we actually use addCleanup inside of setUp of TestContextDecorator?