chroot: make sure the proxy settings we need for apt-cacher-ng, are not copied to the final image
chroot: make sure the proxy settings we need for apt-cacher-ng, are not copied to the final image

fixes: https://github.com/RobertCNelson/omap-image-builder/issues/107
Signed-off-by: Robert Nelson <d6c41255011d14bfa93d8562b946ca186cfa0c7b@gmail.com>

RobertCNelson/omap-image-builder,miloh/image-builder,beagleboard/image-builder,miloh/image-builder,RobertCNelson/omap-image-builder,beagleboard/image-builder