2-f device confirmation dialog breaks redirect flow

[Simon Poirier]

The occasional dialog to confirm TOTP/HOTP authentication devices breaks the login redirection flow.

Steps to reproduce:

1. Connect to an Ubuntu-SSO authenticated resource (e.g. launchpad page)
2. get redirected to SSO
3. login
4. Assuming it's been long enough since last time, you will get a prompt to confirm your 2FA devices.
5. Confirm

Expected result:

Getting redirected to the initial resource (e.g. launchpad page)

Actual result:

Getting redirected to login.ubuntu.com.
Trying to access the original resource again works, but implies potentially having to go back in history and re-clicking the resource link, which creates an awkward experience.