This is to deal with distros like Arch which take /usr merge to the
extreme and set their $PATH to something like /usr/local/bin:/usr/bin
(no /usr/sbin, no /{s,}bin), which breaks our rather inflexible nsroot
population logic.
Signed-off-by: Ivan Shapovalov <intelfx@intelfx.name>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>