Desired behavior:
On Windows 10 using Cypress v4.0.0, the Test Runner doesn't now show Firefox as an option in the browser list.

Looking at the browser configuration, Firefox is not listed.

I copied the Firefox directory (C:\Program Files\Mozilla Firefox) to the AppData directory
..\AppData\Roaming\Cypress\cy\production\browsers
This doesn't update the browser list.
Versions
4.0.0
Desired behavior:
On Windows 10 using Cypress v4.0.0, the Test Runner doesn't now show Firefox as an option in the browser list.
Looking at the browser configuration, Firefox is not listed.

I copied the Firefox directory (C:\Program Files\Mozilla Firefox) to the AppData directory
..\AppData\Roaming\Cypress\cy\production\browsers
This doesn't update the browser list.
Versions
4.0.0