If the viewer has already rezzed any attachments itself, then ignore the simulator-side rez attachments call.

This is a further effort to reduce v3 viewer race conditions where this call may clash with the viewer signalling attachment wearing from its current outfit folder.

OpenSim/Region/CoreModules/Avatar/Attachments/AttachmentsModule.cs

@@ -182,10 +182,6 @@ namespace OpenSim.Region.CoreModules.Avatar.Attachments
             }
         }
 
-        /// <summary>
-        /// RezAttachments. This should only be called upon login on the first region.
-        /// Attachment rezzings on crossings and TPs are done in a different way.
-        /// </summary>
         public void RezAttachments(IScenePresence sp)
         {
             if (!Enabled)
@@ -194,6 +190,16 @@ namespace OpenSim.Region.CoreModules.Avatar.Attachments
             if (null == sp.Appearance)
             {
                 m_log.WarnFormat("[ATTACHMENTS MODULE]: Appearance has not been initialized for agent {0}", sp.UUID);
+
+                return;
+            }
+
+            if (sp.GetAttachments().Count > 0)
+            {
+//                m_log.DebugFormat(
+//                    "[ATTACHMENTS MODULE]: Not doing simulator-side attachment rez for {0} in {1} as their viewer has already rezzed attachments", 
+//                    m_scene.Name, sp.Name);
+
                   return;
             }
 

OpenSim/Region/Framework/Interfaces/IAttachmentsModule.cs

@@ -53,6 +53,10 @@ namespace OpenSim.Region.Framework.Interfaces
         /// RezAttachments. This should only be called upon login on the first region.
         /// Attachment rezzings on crossings and TPs are done in a different way.
         /// </summary>
+        /// <remarks>
+        /// This is only actually necessary for viewers which do not have a current outfit folder (these viewers make
+        /// their own attachment calls on login) and agents which have attachments but no viewer (e.g. NPCs).
+        /// </remarks>
         /// <param name="sp"></param>
         void RezAttachments(IScenePresence sp);
 

OpenSim/Region/Framework/Scenes/ScenePresence.cs

@@ -953,13 +953,11 @@ namespace OpenSim.Region.Framework.Scenes
             // haven't started yet.
             if (PresenceType == PresenceType.Npc || (TeleportFlags & TeleportFlags.ViaLogin) != 0)
             {
-                // We leave a 5 second pause before attempting to rez attachments to avoid a clash with 
+                // Viewers which have a current outfit folder will actually rez their own attachments.  However,
-                // version 3 viewers that maybe doing their own attachment rezzing related to their current
+                // viewers without (e.g. v1 viewers) will not, so we still need to make this call.
-                // outfit folder on startup.  If these operations do clash, then the symptoms are invisible
-                // attachments until one zooms in on the avatar.
                 // 
-                // We do not pause if we are launching on the same thread anyway in order to avoid pointlessly
+                // However, we leave a 5 second pause to try and avoid a clash with viewers that are rezzing 
-                // delaying any attachment related regression tests.
+                // attachments themselves.  This should then mean that this call ends up doing nothing.
                 if (Scene.AttachmentsModule != null)
                     Util.FireAndForget(
                         o =>