[folks] Add a missing yield to make group changes async in the telepathy backend

[Philip Withnall <pwithnall src gnome org>]

commit 336f592c771c8fb852f5b3035bdd162b2ad19a21
Author: Philip Withnall <philip withnall collabora co uk>
Date:   Wed Aug 25 16:45:49 2010 +0100

    Add a missing yield to make group changes async in the telepathy backend

 backends/telepathy/tpf-persona.vala |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/backends/telepathy/tpf-persona.vala b/backends/telepathy/tpf-persona.vala
index 955b2e0..603943b 100644
--- a/backends/telepathy/tpf-persona.vala
+++ b/backends/telepathy/tpf-persona.vala
@@ -143,8 +143,9 @@ public class Tpf.Persona : Folks.Persona,
     {
       if (_change_group (group, is_member))
         {
-          ((Tpf.PersonaStore) this.store).change_group_membership (this, group,
-            is_member);
+          Tpf.PersonaStore store = (Tpf.PersonaStore) this.store;
+
+          yield store.change_group_membership (this, group, is_member);
 
           this.group_changed (group, is_member);
         }