To reproduce the issue follow the steps:
1. create a new project
2. Open a folder in the project view
3. Make sure there are a few folders under the assets folder directory
3. Select the last folder item in the list
4. Press the left arrow
5. It goes up item in the list (which is the same thing the up arrow does)

Expected behavior: It should go to the parent directory

Regression from Unity 5.2
Not reproducible in 5.2.0p1 (cd0778e591b3), 5.2.1p4 (9a78a9ce1e6c)