In the debug image, declare /busybox as a volume so that it is automatically whitelisted, because we don't want to delete it when building multi-stages images.
FYI this is required when using Jenkins, because we need to use the debug kaniko image to be able to start the container "doing nothing" (with /busybox/cat) before building (by executing /kaniko/executor directly inside the container)
See https://issues.jenkins-ci.org/browse/JENKINS-52576
Vincent Behar
priyawadhwa
Nicolas Byl