correct /proc/sys readonly detection
correct /proc/sys readonly detection

barthy1/docker-image-resource,concourse/docker-image-resource,SillyMoo/docker-image-resource,ggeorgiev/docker-image-resource,barthy1/docker-image-resource,SillyMoo/docker-image-resource,ggeorgiev/docker-image-resource,concourse/docker-image-resource