Add test step to test pushing after a previous screen is made current.

osu.Game.Tests/Visual/TestCaseScreenBreadcrumbs.cs

@@ -1,6 +1,7 @@
 // Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
 // Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
 
+using System.Linq;
 using NUnit.Framework;
 using osu.Framework.Allocation;
 using osu.Framework.Graphics;
@@ -64,6 +65,8 @@ namespace osu.Game.Tests.Visual
             });
 
             assertCurrent();
+            pushNext();
+            AddAssert(@"assert there are only 2 items", () => breadcrumbs.Items.Count() == 2);
         }
 
         [BackgroundDependencyLoader]

osu.Game/Graphics/UserInterface/BreadcrumbControl.cs

@@ -47,6 +47,7 @@ namespace osu.Game.Graphics.UserInterface
 
             public override bool HandleKeyboardInput => State == Visibility.Visible;
             public override bool HandleMouseInput => State == Visibility.Visible;
+            public override bool IsRemovable => true;
 
             private Visibility state;