- Enforced no user or agent with UUID 0 on agent DB insertion

OpenSim/Data/Tests/BasicUserTest.cs

@@ -226,6 +226,9 @@ namespace OpenSim.Data.Tests
             Assert.That(user4,Is.EqualTo(a0a.ProfileID));
             Assert.That(agent4,Is.EqualTo(a4a.SessionID));
             Assert.That(zero,Is.EqualTo(a4a.ProfileID));
+
+            Assert.That(db.GetAgentByUUID(user4),Is.Null);
+            Assert.That(db.GetAgentByUUID(zero),Is.Null);
         }
         
         [Test]