[folks] tracker: Ensure the Tracker connection is disposed in test teardown

[Philip Withnall <pwithnall src gnome org>]

commit f18239080b4f3f73fd7a4d303a0afc1ab9f066fe
Author: Philip Withnall <philip tecnocode co uk>
Date:   Sat Jun 21 18:20:49 2014 +0100

    tracker: Ensure the Tracker connection is disposed in test teardown
    
    This was causing the Tracker tests to fail.

 tests/lib/tracker/backend.vala |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/tests/lib/tracker/backend.vala b/tests/lib/tracker/backend.vala
index 64c69e5..1ebfe49 100644
--- a/tests/lib/tracker/backend.vala
+++ b/tests/lib/tracker/backend.vala
@@ -32,7 +32,7 @@ public class TrackerTest.Backend
   public static const string URLS = "nco:urls";
   public bool debug { get; set; }
   private GLib.List<Gee.HashMap<string, string>> _contacts;
-  private Tracker.Sparql.Connection _connection;
+  private Tracker.Sparql.Connection? _connection;
 
 
   public Backend ()
@@ -50,7 +50,8 @@ public class TrackerTest.Backend
   /* Remove contacts */
   public void tear_down ()
     {
-
+      this.reset ();
+      this._connection = null;
     }
 
   public void reset ()