Fix test to accept both orderings of the cache-control header

wagtail/documents/tests/test_views.py

@@ -67,7 +67,7 @@ class TestServeView(TestCase):
         self.assertEqual(self.get()['ETag'], '"123456"')
 
     def test_has_cache_control_header(self):
-        self.assertEqual(self.get()['Cache-Control'], 'max-age=3600, public')
+        self.assertIn(self.get()['Cache-Control'], ['max-age=3600, public', 'public, max-age=3600'])
 
     def clear_sendfile_cache(self):
         from wagtail.utils.sendfile import _get_sendfile