Account for DbContext tracking

[soljarka]

When I send several queries with similar arguments yet different asOf timestamps using a single instance of DbContext, I always get similar results, apparently because of tracking. I solve this issue in my code by adding AsNoTracking():

        public static IQueryable<TSource> AsOfConditional<TSource>(this IQueryable<TSource> source, DateTime? asOf)
        where TSource : class
        {
            if (asOf.HasValue)
                return source.AsOf(asOf.Value).AsNoTracking();

            return source;
        }

This may be not the responsibility of this library, but it might be helpful to extend AsOf() or at least give users some hints.