[folks] telepathy: Clarify nullability of Tpf.PersonaStore._conn

[Jeremy Whiting <jpwhiting src gnome org>]

commit d556feac0e2551151f4168ba2da5ff73f1751f72
Author: Philip Withnall <philip tecnocode co uk>
Date:   Sun Sep 2 21:20:31 2012 +0100

    telepathy: Clarify nullability of Tpf.PersonaStore._conn

 backends/telepathy/lib/tpf-persona-store.vala |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/backends/telepathy/lib/tpf-persona-store.vala b/backends/telepathy/lib/tpf-persona-store.vala
index eb152d6..74c8ce0 100644
--- a/backends/telepathy/lib/tpf-persona-store.vala
+++ b/backends/telepathy/lib/tpf-persona-store.vala
@@ -62,7 +62,7 @@ public class Tpf.PersonaStore : Folks.PersonaStore
    * this should *not* be cleared in _reset(). */
   private HashMap<string, File> _avatars = new HashMap<string, File> ();
 
-  private Connection _conn;
+  private Connection? _conn; /* null when disconnected */
   private AccountManager? _account_manager; /* only null before prepare() */
   private Logger _logger;
   private Persona? _self_persona;