Fixed isolation of test_check_errors_catches_all_exceptions.

tests/utils_tests/test_autoreload.py

@@ -98,8 +98,11 @@ class TestIterModulesAndFiles(SimpleTestCase):
         filename = self.temporary_file('test_exception.py')
         filename.write_text('raise Exception')
         with extend_sys_path(str(filename.parent)):
+            try:
                 with self.assertRaises(Exception):
                     autoreload.check_errors(import_module)('test_exception')
+            finally:
+                autoreload._exception = None
         self.assertFileFound(filename)
 
     def test_zip_reload(self):