[CentOS] repair systemd-nspawn

    systemd-nspawn fails in C7 with
     
    ------------ nspawn error --------
    sudo  systemd-nspawn
    Spawning namespace container on /mnt/usb (console is /dev/pts/1).
    Init process in the container running as PID 1799.
    Failed to open system bus: No such file or directory
    Failed to open system bus: No such file or directory
    Container failed with error code 254.
    -------------- snip -----------
     
    With strace I noticed that the file below is not found:
     
    to /etc/rc.local add:
    ------------ /etc/rc.local ---------
    if [ ! -f /run/dbus/system_bus_socket ]; then
    mkdir -p /run/dbus
    LST=`pwd`
    cd /run/dbus
    ln -s /var/run/dbus/system_bus_socket system_bus_socket
    cd $LST
    fi
    ------------ snip ----------
     
    Author:
    PryMar56 on freenode
    #xen,#centos