It's a xenial chroot and it indeed doesn't have that test in keyboard-configuration.postinst. Perhaps just an ubuntu issue then, sorry for the noise. ;-)
- Bug#851189: keyboard-configuration: ALT+Cursor-Left switch... Mike McGuire
- Bug#851189: keyboard-configuration: ALT+Cursor-Left s... Samuel Thibault
- Bug#851189: keyboard-configuration: ALT+Cursor-Le... Mike McGuire
- Bug#851189: keyboard-configuration: ALT+Curso... Samuel Thibault
- Bug#851189: keyboard-configuration: ALT+C... Mike McGuire