BoxIO : only unpromote plug if the Box's children are readable
BoxIO : only unpromote plug if the Box's children are readable

andrewkaufman/gaffer,ivanimanishi/gaffer,lucienfostier/gaffer,lucienfostier/gaffer,johnhaddon/gaffer,ImageEngine/gaffer,lucienfostier/gaffer,hradec/gaffer,boberfly/gaffer,johnhaddon/gaffer,johnhaddon/gaffer,GafferHQ/gaffer,hradec/gaffer,ImageEngine/gaffer,appleseedhq/gaffer,appleseedhq/gaffer,boberfly/gaffer,hradec/gaffer,johnhaddon/gaffer,ivanimanishi/gaffer,ImageEngine/gaffer,hradec/gaffer,ImageEngine/gaffer,hradec/gaffer,johnhaddon/gaffer,andrewkaufman/gaffer,appleseedhq/gaffer,boberfly/gaffer,GafferHQ/gaffer,GafferHQ/gaffer,GafferHQ/gaffer,ivanimanishi/gaffer,GafferHQ/gaffer,andrewkaufman/gaffer,andrewkaufman/gaffer,ivanimanishi/gaffer,appleseedhq/gaffer,lucienfostier/gaffer,boberfly/gaffer,andrewkaufman/gaffer