This issue is explained here : https://lists.yoctoproject.org/pipermail/yocto/2016-April/029605.html and here : https://lists.yoctoproject.org/pipermail/yocto/2016-April/029594.html and has been fixed by Bruce Ashfield here : http://www.crashcourse.ca/wiki/index.php/WRL8_cfg_bug
http://www.crashcourse.ca/wiki/index.php/WRL8_cfg_bug