[Bug]: Sort is preventing empty change notifications despite "suppressEmptyChangeSets: false" on Connect

[MagneticLlama]

Describe the bug 🐞

After using Connect with "suppressEmptyChangeSets: false" on an empty SourceCache, Sort will cause the suppression empty of change sets. In the reproduction steps, Subscribe callbacks will not be hit unless Sort is removed.

Step to reproduce

var sourceCache = new SourceCache<Item, int>(p => p.Id);
sourceCache.Connect(suppressEmptyChangeSets: false)
    .Sort(SortExpressionComparer<Item>.Descending(x => x.Id))
    .Bind(out items)
    .Subscribe(x =>
    {
        Console.WriteLine($"Got {items.Count} results");
    });

Expected behavior

Subscribe's onNext and onCompleted should trigger even if the SourceCache is empty when suppressEmptyChangeSets is set to false on Connect.

[RolandPheasant]

Good spot.

[github-actions]

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