System Information
Operating system: Windows 10 - 64bits
Graphics card: Nvidia Quadro K4200

Blender Version
Branch: Blender 2.8
Date: 2018 12-12 01:18
Hash: 16fc62e15f0

Short description of error
Select Tool and Box Select Tool are not working as expected in Armature Edit Mode. The expected behavior is a New selection as it is configured in the Input (see screenshot).

Note: Shift + Tweak Left for Add selection works correctly. And so does Ctrl + Tweak Left for Substract selection.

Exact steps for others to reproduce the error

1. Create bone
2. Go into Edit Mode
3. Create a few other bones (by duplicating for example)
4. Choose Select Tool or Box Select Tool (try both)
5. Left click tweak to create the box selection
6. Problem: you can't select the bones