Slightly improving the tag merging test

apps/rp/tests/test_article.py

@@ -216,7 +216,7 @@ class TestArticleViews(TestCase):
         a = Article.objects.get(pk=pk)
         assert r.status_code == 302  # We're redirecting to the view or preview of the article
         assert a.title == 'Zog Zog'
-        assert set(a.tags.names()) == {"merged tag"}
+        assert set(a.tags.names()) == set(self.articles[0].tags.names()) | {"merged tag"}
 
 
 class TestArticleApi(TestCase):