Mantis#2067. Thank you kindly, HomerHorwitz for a patch that:

Found that during my ghost-hunt: Add some logging and you see that the 
counting down happens twice (once at the place that is removed by the 
patch, and once caused by the actual removal of the root-/child-agent 
during LLClientView.Close). With the patch applied, I end up with correct 
numbers, i.e. with 0 roots and 0 children after everyone has logged out.

1 files changed, 9 insertions, 8 deletions

diff --git a/OpenSim/Region/Environment/Scenes/Scene.cs b/OpenSim/Region/Environment/Scenes/Scene.cs
index 0bd0028..2b8bbbd 100644
--- a/OpenSim/Region/Environment/Scenes/Scene.cs
+++ b/OpenSim/Region/Environment/Scenes/Scene.cs
@@ -2767,14 +2767,15 @@ namespace OpenSim.Region.Environment.Scenes
                 ScenePresence presence = m_innerScene.GetScenePresence(agentID);
                 if (presence != null)
                 {
-                    if (presence.IsChildAgent)
-                    {
-                        m_innerScene.removeUserCount(false);
-                    }
-                    else
-                    {
-                        m_innerScene.removeUserCount(true);
-                    }
+                    // Nothing is removed here, so down count it as such
+                    // if (presence.IsChildAgent)
+                    // {
+                    //    m_innerScene.removeUserCount(false);
+                    // }
+                    // else
+                    // {
+                    //    m_innerScene.removeUserCount(true);
+                    // }
 
                     // Tell a single agent to disconnect from the region.
                     presence.ControllingClient.SendShutdownConnectionNotice();