Fix NH-2584

SVN: trunk@5494

Author: fabiomaulo

src/NHibernate.Test/LazyProperty/LazyPropertyFixture.cs

@@ -116,5 +116,19 @@ public void CanGetValueForNonLazyProperty()
 			}
 		}
 
+		[Test]
+		public void CanLoadAndSaveObjectInDifferentSessions()
+		{
+			Book book;
+			using (ISession s = OpenSession())
+			{
+				book = s.Get<Book>(1);
+			}
+
+			using (ISession s = OpenSession())
+			{
+				s.Merge(book);
+			}
+		}
 	}
 }

src/NHibernate/Event/Default/DefaultMergeEventListener.cs

@@ -124,6 +124,10 @@ public virtual void OnMerge(MergeEvent @event, IDictionary copiedAlready)
 
 					@event.Entity = entity;
 					EntityState entityState = EntityState.Undefined;
+					if (ReferenceEquals(null, @event.EntityName))
+					{
+						@event.EntityName = source.BestGuessEntityName(entity);
+					}
 
 					// Check the persistence context for an entry relating to this
 					// entity to be merged...