Comment 6 for bug 1039155

I suspect that we want /etc/X11/Xsession.d/50_check_unity_support to be something like this (untested):

# This file is sourced by Xsession(5), not executed.
# Select the right session if we have already done
# an unity check, try to check it other

if [ "x$DESKTOP_SESSION" = "xubuntu" ] && [ ! -f "/tmp/unity_support_test.0" ]; then
    if [ -f "/tmp/unity_support_test.1" ]; then
        export LIBGL_ALWAYS_SOFTWARE=1
    else
        /usr/lib/nux/unity_support_test
        if [ $? -ne 0 ]; then
     export LIBGL_ALWAYS_SOFTWARE=1
        fi
    fi
fi