Steps to reproduce:

1. Create new project
2. Create empty game object and add 3 child object to it
3. Expand this hierarchy
4. Select last child and press left arrow key
5. Notice that sibling hihgher in hierarchy is selected
Expected behaviour - Parent game object is selected

Note: Same thing when pressing right arrow key, after hierarchy is expanded - siblings are getting selected

Reproduced with: 5.3.0f4, 5.4.0a6
Regression introduced in 5.3.0f1 (previously - null reference exceptions were thrown)
Not reproducible: 5.2.3p2