Non-US keyboard layout selected with Greeter sometimes is not active when logged in

Reported by two users, happening from Tails 1.1

Steps to reproduce:

- Choose a different keyboard layout at boot (not language).

Error:

- Not always, but sometimes the layout active when logged in is English. Keyboard layout is present on the top bar, so you can activate your desired layout clicking on it.

Desired result:

- Always have the chosen keyboard layout active when logged.

Related issues

• Related to #7065 (closed)
• Related to #8713 (closed)
• Related to #9336 (closed)

Original created by @emmapeel on 7912 (Redmine)