ubuntu - Docker install forces QWERTY keyboard configuration?

I've installed Docker on a fresh empty copy of Ubuntu 14.04 mounted under VirtualBox.

sudo apt-get -y install docker.io

However, when I log out and in again, the AZERTY keyboard is switched to QWERTY. I can switch it back to normal, but the QWERTY keeps coming up after logout...

setxkbmap fr

Any clue why this behaviour?

My host computer runs Linux LMDE, and I mounted Ubuntu 14.04 in VirtualBox 5.0.2, with the English language and the French AZERTY keyboard.

Thanks for your help