Right mouse button as primary stopped working

[Victor gonzalez]

Story: I think this feature was working not long ago, but now set the right mouse button does nothing, only the left works as primary.

Environment: unity8-deb on zesty

STEPS:

1. Go to uss>mouse&touchpad
2. Set right mouse button as primary
3. Try to click other checkboxes or slide cursor/finger scrolling with right mouse button

Expected result: right mouse button should start working as primary so you can click/slide everything with it
Current result: left mouse button is always set as primary