[folks] Make a result argument nullable

[Philip Withnall <pwithnall src gnome org>]

commit e15bae8f525c3c0b87f1694ed71ba4011aa4ff9e
Author: Philip Withnall <philip withnall collabora co uk>
Date:   Thu Sep 16 11:58:36 2010 +0100

    Make a result argument nullable
    
    Since there is no .finish() method for this async function, and the result
    is always NULL, the result argument should be nullable. This prevents it
    spewing warnings.

 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 3ae4bd8..3652c40 100644
--- a/backends/telepathy/lib/tpf-persona-store.vala
+++ b/backends/telepathy/lib/tpf-persona-store.vala
@@ -381,7 +381,7 @@ public class Tpf.PersonaStore : Folks.PersonaStore
     }
 
   private void new_group_channels_cb (TelepathyGLib.Channel? channel,
-      GLib.AsyncResult result)
+      GLib.AsyncResult? result)
     {
       if (channel == null)
         {