Repro steps:
1. Open "Click Select" project
2. Open "Selecting Objects" scene
3. Click on a cube
4. Make sure that Translate or Scale box is not selected
5. Observe that once you click the cube it selects the Plane object
Note: GIF attached

Actual behavior: Clicking on a 3D object but not selecting the Translate or Scale box selects the object behind it
Expected: Clicking on a 3D object but not selecting the Translate or Scale box does not select the object behind it

Reproduced on: 5.5.0a5, 5.4.0p1, 5.4.0f3, 5.3.6p2, 5.2.4f1
Didn't reproduce on: 5.1.4f1