Fix SessionTagPrefetchEntitySetTest

Author: SergeiPavlov

Orm/Xtensive.Orm/Orm/Internals/Prefetch/EntitySetTask.cs

@@ -171,6 +171,11 @@ private QueryTask CreateQueryTask()
       var session = manager.Owner.Session;
       var scope = new CompiledQueryProcessingScope(null, null, parameterContext, false);
       QueryProvider = (CompilableProvider) session.StorageNode.InternalQueryCache.GetOrAdd(key, generator);
+      if (session.Tags != null) {
+        foreach (var tag in session.Tags) {
+          QueryProvider = new TagProvider(QueryProvider, tag);
+        }
+      }
       ExecutableProvider executableProvider;
       using (scope.Enter()) {
         executableProvider = session.Compile(QueryProvider);