In Scene.Close(), dispose of the physics scene after base.Close() since script events can still access Physics scene until the script engine shuts down (triggered off base.Close())

XEngine listeners to EventManager.OnShutdown which is triggered from base.Close().
Possibly it could listen for the earlier OnSceneShuttingDown instead, but the easier solution right now is to relocate disposal of the physics scene.
This bug has existed since c150320 (Thu Jul 26 15:27:18 2012) and was in 0.7.4

OpenSim/Region/Framework/Scenes/Tests/SceneTests.cs

@@ -65,5 +65,22 @@ namespace OpenSim.Region.Framework.Scenes.Tests
             
             Assert.That(scene.Frame, Is.EqualTo(1));
         }
+
+        [Test]
+        public void TestShutdownScene()
+        {
+            TestHelpers.InMethod();
+
+            Scene scene = new SceneHelpers().SetupScene();
+            scene.Close();
+
+            Assert.That(scene.ShuttingDown, Is.True);
+            Assert.That(scene.Active, Is.False);
+
+            // Trying to update a shutdown scene should result in no update
+            scene.Update(1);
+
+            Assert.That(scene.Frame, Is.EqualTo(0));
+        }
     }
 }