Prevent double ground collisions and prefer the physics result if there is one.

ODE is known to not see the ground sometimes on raycast so the double test is
needed.

OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs

@@ -12287,12 +12287,24 @@ namespace OpenSim.Region.ScriptEngine.Shared.Api
                 }
             }
 
+            // Double check this
             if (checkTerrain)
+            {
+                bool skipGroundCheck = false;
+
+                foreach (ContactResult c in results)
+                {
+                    if (c.ConsumerID == 0) // Physics gave us a ground collision
+                        skipGroundCheck = true;
+                }
+
+                if (!skipGroundCheck)
                 {
                     ContactResult? groundContact = GroundIntersection(rayStart, rayEnd);
                     if (groundContact != null)
                         results.Add((ContactResult)groundContact);
                 }
+            }
 
             results.Sort(delegate(ContactResult a, ContactResult b)
             {