Implement ability for hg logins to try fallback regions just like local logins.

These would be specified in the [GridService] section of Robust.HG.ini, which already lists these in the example text.
Untested patch so that Neb can easily pull in for testing, though shouldn't disrupt existing hg logins since fallback processing is a bit of code stuck on the end of the login sequence.

OpenSim/Services/HypergridService/GatekeeperService.cs

@@ -326,7 +326,7 @@ namespace OpenSim.Services.HypergridService
                 return false;
             }
 
-            m_log.DebugFormat("[GATEKEEPER SERVICE]: User is OK");
+            m_log.DebugFormat("[GATEKEEPER SERVICE]: User {0} is ok", aCircuit.Name);
 
             bool isFirstLogin = false;
             //
@@ -345,7 +345,7 @@ namespace OpenSim.Services.HypergridService
                         aCircuit.firstname, aCircuit.lastname);
                     return false;
                 }
-                m_log.DebugFormat("[GATEKEEPER SERVICE]: Login presence ok");
+                m_log.DebugFormat("[GATEKEEPER SERVICE]: Login presence {0} is ok", aCircuit.Name);
 
                 // Also login foreigners with GridUser service
                 if (m_GridUserService != null && account == null)
@@ -376,7 +376,8 @@ namespace OpenSim.Services.HypergridService
                 reason = "Destination region not found";
                 return false;
             }
-            m_log.DebugFormat("[GATEKEEPER SERVICE]: destination ok: {0}", destination.RegionName);
+            m_log.DebugFormat(
+                "[GATEKEEPER SERVICE]: Destination {0} is ok for {1}", destination.RegionName, aCircuit.Name);
 
             //
             // Adjust the visible name
@@ -410,8 +411,41 @@ namespace OpenSim.Services.HypergridService
             // Preserve our TeleportFlags we have gathered so-far
             loginFlag |= (Constants.TeleportFlags) aCircuit.teleportFlags;
 
-            m_log.DebugFormat("[GATEKEEPER SERVICE]: launching agent {0}", loginFlag);
-            return m_SimulationService.CreateAgent(destination, aCircuit, (uint)loginFlag, out reason);
+            m_log.DebugFormat("[GATEKEEPER SERVICE]: Launching {0} {1}", aCircuit.Name, loginFlag);
+
+            bool success = m_SimulationService.CreateAgent(destination, aCircuit, (uint)loginFlag, out reason);
+
+            if (!success)
+            {
+                List<GridRegion> fallbackRegions = m_GridService.GetFallbackRegions(account.ScopeID, destination.RegionLocX, destination.RegionLocY);
+                if (fallbackRegions != null)
+                {
+                    // Try the fallback regions
+                    m_log.DebugFormat(
+                        "[GATEKEEPER SERVICE]: Could not successfully log agent {0} into {1}.  Trying fallback regions.", 
+                        aCircuit.Name, destination.RegionName);
+
+                    foreach (GridRegion fallbackRegion in fallbackRegions)
+                    {
+                        m_log.DebugFormat(
+                            "[GATEKEEPER SERVICE]: Trying fallback region {0} for {1}", 
+                            fallbackRegion.RegionName, aCircuit.Name);
+
+                        success = m_SimulationService.CreateAgent(fallbackRegion, aCircuit, (uint)loginFlag, out reason);
+
+                        if (success)
+                            break;
+                    }
+                }
+                else
+                {
+                    m_log.DebugFormat(
+                        "[GATEKEEPER SERVICE]: Could not successfully log agent {0} into {1} and no fallback regions to try.", 
+                        aCircuit.Name, destination.RegionName);
+                }
+            }
+
+            return success;
         }
 
         protected bool Authenticate(AgentCircuitData aCircuit)