Xorg loads keyboard layout for new devices (or existing one re-detected)
only from its config, ignoring runtime changes done in the meantime
(setxkbmap etc). Since installation process calls udevadm trigger
somewhere, all input devices are re-discovered and reverted to default
keyboard layout (us). Avoid this by configuring current keyboard layout
also as udev rules, which are loaded by Xorg while discovering device.
FixesQubesOS/qubes-issues#3352