Do not allow a script to attach a prim if its being sat upon.

This prevents a stack overflow where a get position on the avatar will refer to the attachment which will in turn refer back to the avatar.
This required recording of all sitting avatars on a prim which is done separately from recording the sit target avatar.
Recording HashSet is null if there are no sitting avatars in order to save memory.

OpenSim/Tests/Common/Helpers/SceneHelpers.cs

@@ -412,26 +412,49 @@ namespace OpenSim.Tests.Common
         /// <returns></returns>
         public static AgentCircuitData GenerateAgentData(UUID agentId)
         {
-            string firstName = "testfirstname";
+            AgentCircuitData acd = GenerateCommonAgentData();
 
-            AgentCircuitData agentData = new AgentCircuitData();
-            agentData.AgentID = agentId;
-            agentData.firstname = firstName;
-            agentData.lastname = "testlastname";
+            acd.AgentID = agentId;
+            acd.firstname = "testfirstname";
+            acd.lastname = "testlastname";
+            acd.ServiceURLs = new Dictionary<string, object>();
+
+            return acd;
+        }
+
+        /// <summary>
+        /// Generate some standard agent connection data.
+        /// </summary>
+        /// <param name="agentId"></param>
+        /// <returns></returns>
+        public static AgentCircuitData GenerateAgentData(UserAccount ua)
+        {
+            AgentCircuitData acd = GenerateCommonAgentData();
+
+            acd.AgentID = ua.PrincipalID;
+            acd.firstname = ua.FirstName;
+            acd.lastname = ua.LastName;
+            acd.ServiceURLs = ua.ServiceURLs;
+
+            return acd;
+        }
+
+        private static AgentCircuitData GenerateCommonAgentData()
+        {
+            AgentCircuitData acd = new AgentCircuitData();
 
             // XXX: Sessions must be unique, otherwise one presence can overwrite another in NullPresenceData.
-            agentData.SessionID = UUID.Random();
-            agentData.SecureSessionID = UUID.Random();
+            acd.SessionID = UUID.Random();
+            acd.SecureSessionID = UUID.Random();
 
-            agentData.circuitcode = 123;
-            agentData.BaseFolder = UUID.Zero;
-            agentData.InventoryFolder = UUID.Zero;
-            agentData.startpos = Vector3.Zero;
-            agentData.CapsPath = "http://wibble.com";
-            agentData.ServiceURLs = new Dictionary<string, object>();
-            agentData.Appearance = new AvatarAppearance();
+            acd.circuitcode = 123;
+            acd.BaseFolder = UUID.Zero;
+            acd.InventoryFolder = UUID.Zero;
+            acd.startpos = Vector3.Zero;
+            acd.CapsPath = "http://wibble.com";
+            acd.Appearance = new AvatarAppearance();
 
-            return agentData;
+            return acd;
         }
 
         /// <summary>
@@ -440,6 +463,9 @@ namespace OpenSim.Tests.Common
         /// <remarks>
         /// This can be used for tests where there is only one region or where there are multiple non-neighbour regions
         /// and teleport doesn't take place.
+        ///
+        /// XXX: Use the version of this method that takes the UserAccount structure wherever possible - this will
+        /// make the agent circuit data (e.g. first, lastname) consistent with the user account data.
         /// </remarks>
         /// <param name="scene"></param>
         /// <param name="agentId"></param>
@@ -452,6 +478,10 @@ namespace OpenSim.Tests.Common
         /// <summary>
         /// Add a root agent where the details of the agent connection (apart from the id) are unimportant for the test
         /// </summary>
+        /// <remarks>
+        /// XXX: Use the version of this method that takes the UserAccount structure wherever possible - this will
+        /// make the agent circuit data (e.g. first, lastname) consistent with the user account data.
+        /// </remarks>
         /// <param name="scene"></param>
         /// <param name="agentId"></param>
         /// <param name="sceneManager"></param>
@@ -461,6 +491,17 @@ namespace OpenSim.Tests.Common
             return AddScenePresence(scene, GenerateAgentData(agentId), sceneManager);
         }
 
+        /// <summary>
+        /// Add a root agent.
+        /// </summary>
+        /// <param name="scene"></param>
+        /// <param name="ua"></param>
+        /// <returns></returns>
+        public static ScenePresence AddScenePresence(Scene scene, UserAccount ua)
+        {
+            return AddScenePresence(scene, GenerateAgentData(ua));
+        }
+
         /// <summary>
         /// Add a root agent.
         /// </summary>

OpenSim/Tests/Common/Helpers/UserAccountHelpers.cs

@@ -138,6 +138,15 @@ namespace OpenSim.Tests.Common
             CreateUserWithInventory(scene, ua, pw);
             return ua;
         }
+
+        public static UserAccount CreateUserWithInventory(
+            Scene scene, string firstName, string lastName, int userId, string pw)
+        {
+            UserAccount ua
+                = new UserAccount(TestHelpers.ParseTail(userId)) { FirstName = firstName, LastName = lastName };
+            CreateUserWithInventory(scene, ua, pw);
+            return ua;
+        }
         
         public static void CreateUserWithInventory(Scene scene, UserAccount ua, string pw)
         {