-        assert (picture.picture_info.about == valid_about,
-                _("rdf:about is not") + " " + valid_about)
+        assert picture.picture_info.about in valid_about, \
+                _("rdf:about is not") + " " + valid_about[0]
+
+    def publishable_error(self):
+        try:
+            return self.assert_publishable()
+        except AssertionError, e:
+            return e
+        else:
+            return None