Add initializing m_scene if it's not null. Marking MyScene as [Obsolete]

because it will be removed soonish. This is NOT the way to go.
Thanks, mpallari, for pointing this out.
Fixes Mantis #3684

OpenSim/Region/CoreModules/Agent/AssetTransaction/AssetTransactionModule.cs

@@ -41,6 +41,7 @@ namespace OpenSim.Region.CoreModules.Agent.AssetTransaction
         private bool m_dumpAssetsToFile = false;
         private Scene m_scene = null;
 
+        [Obsolete]
         public Scene MyScene
         {
             get{ return m_scene;}
@@ -70,6 +71,12 @@ namespace OpenSim.Region.CoreModules.Agent.AssetTransaction
 
                 scene.EventManager.OnNewClient += NewClient;
             }
+
+            // EVIL HACK!
+            // This needs killing!
+            //
+            if (m_scene == null)
+                m_scene = scene;
         }
 
         public void PostInitialise()