mod_vcard_legacy: Advertise lack of avatar correctly (fixes #1431) (thanks lovetox)

plugins/mod_vcard_legacy.lua

@@ -301,10 +301,10 @@ local function inject_xep153(event)
 	local pep_service = mod_pep.get_pep_service(username);
 
 	stanza:remove_children("x", "vcard-temp:x:update");
-	local x_update = st.stanza("x", { xmlns = "vcard-temp:x:update" });
+	local x_update = st.stanza("x", { xmlns = "vcard-temp:x:update" }):tag("photo");
 	local ok, avatar_hash = pep_service:get_last_item("urn:xmpp:avatar:metadata", true);
 	if ok and avatar_hash then
-		x_update:text_tag("photo", avatar_hash);
+		x_update:text(avatar_hash);
 	end
 	stanza:add_direct_child(x_update);
 end