Fix rewind incorrectly selecting the same beatmap

[ntransw]

Fixes #25904

[peppy]

Please add test coverage (ie. add a test which fails without your change) somewhere around here:

osu/osu.Game.Tests/Visual/SongSelect/TestSceneBeatmapCarousel.cs

Lines 417 to 474 in b884f1a

	/// <summary>
	/// Test random non-repeating algorithm
	/// </summary>
	[Test]
	public void TestRandom()
	{
	loadBeatmaps();
	setSelected(1, 1);
	nextRandom();
	ensureRandomDidntRepeat();
	nextRandom();
	ensureRandomDidntRepeat();
	nextRandom();
	ensureRandomDidntRepeat();
	prevRandom();
	ensureRandomFetchSuccess();
	prevRandom();
	ensureRandomFetchSuccess();
	nextRandom();
	ensureRandomDidntRepeat();
	nextRandom();
	ensureRandomDidntRepeat();
	nextRandom();
	AddAssert("ensure repeat", () => selectedSets.Contains(carousel.SelectedBeatmapSet));
	AddStep("Add set with 100 difficulties", () => carousel.UpdateBeatmapSet(TestResources.CreateTestBeatmapSetInfo(100, rulesets.AvailableRulesets.ToArray())));
	AddStep("Filter Extra", () => carousel.Filter(new FilterCriteria { SearchText = "Extra 10" }, false));
	checkInvisibleDifficultiesUnselectable();
	checkInvisibleDifficultiesUnselectable();
	checkInvisibleDifficultiesUnselectable();
	checkInvisibleDifficultiesUnselectable();
	checkInvisibleDifficultiesUnselectable();
	AddStep("Un-filter", () => carousel.Filter(new FilterCriteria(), false));
	}
	[Test]
	public void TestRewindToDeletedBeatmap()
	{
	loadBeatmaps();
	var firstAdded = TestResources.CreateTestBeatmapSetInfo();
	AddStep("add new set", () => carousel.UpdateBeatmapSet(firstAdded));
	AddStep("select set", () => carousel.SelectBeatmap(firstAdded.Beatmaps.First()));
	nextRandom();
	AddStep("delete set", () => carousel.RemoveBeatmapSet(firstAdded));
	prevRandom();
	AddAssert("deleted set not selected", () => carousel.SelectedBeatmapSet?.Equals(firstAdded) == false);
	}

[peppy]

Needs test

[ntransw]

Added a working test, although I wasn't sure how to populate randomSelectedBeatmaps with duplicates to reproduce the failure outside of just calling nextRandom() excessively.

[bdach]

Test fails on master, so it'll work.

resolved

[bdach]

@ntransw no need to merge master. please read contributing guidelines. now i have to re-approve the CI run that i was gonna see if it passes.