Mantis#852. Thank you kindly, cmickeyb for a patch that:

There appears to be a problem with the mapping of scripts when an llHTTPRequest completes. 
CheckHttpRequests() looks for a function that maps to the localID associated with the http 
request. However, the only context in which it looks is that of the first region. That is,
m_CmdManager.m_ScriptEngine.m_ScriptManager is the same no matter where the script executed 
that initiated the llHTTPRequest. Since scripts appear to be loaded into a region specific 
scriptmanager on startup, the event handler is only found for requests coming from the first region.

OpenSim/Region/ScriptEngine/Common/ScriptEngineBase/AsyncCommandPlugins/XmlRequest.cs

@@ -46,17 +46,24 @@ namespace OpenSim.Region.ScriptEngine.Common.ScriptEngineBase.AsyncCommandPlugin
                 return;
 
             IXMLRPC xmlrpc = m_CmdManager.m_ScriptEngine.World.RequestModuleInterface<IXMLRPC>();
+            if (null == xmlrpc)
+                return;
 
-            if (xmlrpc != null)
+            // Process the completed request queue
-            {
             RPCRequestInfo rInfo = xmlrpc.GetNextCompletedRequest();
 
             while (rInfo != null)
             {
-                    if (m_CmdManager.m_ScriptEngine.m_ScriptManager.GetScript(rInfo.GetLocalID(), rInfo.GetItemID()) != null)
+                bool handled = false;
-                    {
+
+                // Request must be taken out of the queue in case there is no handler, otherwise we loop infinitely
                 xmlrpc.RemoveCompletedRequest(rInfo.GetMessageID()); 
 
+                // And since the xmlrpc request queue is actually shared among all regions on the simulator, we need
+                // to look in each one for the appropriate handler
+                foreach (ScriptEngine sman in ScriptEngine.ScriptEngines) {
+                    if (sman.m_ScriptManager.GetScript(rInfo.GetLocalID(),rInfo.GetItemID()) != null) {
+
                         //Deliver data to prim's remote_data handler
                         object[] resobj = new object[]
                         {
@@ -64,22 +71,37 @@ namespace OpenSim.Region.ScriptEngine.Common.ScriptEngineBase.AsyncCommandPlugin
                             new LSL_Types.LSLInteger(rInfo.GetIntValue()),
                             new LSL_Types.LSLString(rInfo.GetStrVal())
                         };
-                        m_CmdManager.m_ScriptEngine.m_EventQueueManager.AddToScriptQueue(
+                        sman.m_EventQueueManager.AddToScriptQueue(
                             rInfo.GetLocalID(), rInfo.GetItemID(), "remote_data", EventQueueManager.llDetectNull, resobj
                         );
+
+                        handled = true;
+                    }
+                }
+
+                if (! handled)
+                {
+                    Console.WriteLine("Unhandled xml_request: " + rInfo.GetItemID());
                 }
 
                 rInfo = xmlrpc.GetNextCompletedRequest();
             }
 
+            // Process the send queue
             SendRemoteDataRequest srdInfo = xmlrpc.GetNextCompletedSRDRequest();
 
             while (srdInfo != null)
             {
-                    if (m_CmdManager.m_ScriptEngine.m_ScriptManager.GetScript(srdInfo.m_localID, srdInfo.m_itemID) != null)
+                bool handled = false;
-                    {
+
+                // Request must be taken out of the queue in case there is no handler, otherwise we loop infinitely
                 xmlrpc.RemoveCompletedSRDRequest(srdInfo.GetReqID());
                 
+                // And this is another shared queue... so we check each of the script engines for a handler
+                foreach (ScriptEngine sman in ScriptEngine.ScriptEngines)               
+                {
+                    if (sman.m_ScriptManager.GetScript(srdInfo.m_localID,srdInfo.m_itemID) != null) {
+
                         //Deliver data to prim's remote_data handler
                         object[] resobj = new object[]
                         {
@@ -87,14 +109,21 @@ namespace OpenSim.Region.ScriptEngine.Common.ScriptEngineBase.AsyncCommandPlugin
                             new LSL_Types.LSLInteger(srdInfo.idata),
                             new LSL_Types.LSLString(srdInfo.sdata)
                         };
-                        m_CmdManager.m_ScriptEngine.m_EventQueueManager.AddToScriptQueue(
+                        sman.m_EventQueueManager.AddToScriptQueue(
                             srdInfo.m_localID, srdInfo.m_itemID, "remote_data", EventQueueManager.llDetectNull, resobj
                         );
+
+                        handled = true;
+                    }
+                }
+                
+                if (! handled)
+                {
+                    Console.WriteLine("Unhandled xml_srdrequest: " + srdInfo.GetReqID());
                 }
 
                 srdInfo = xmlrpc.GetNextCompletedSRDRequest();
             }
         }
     }
-    }
 }