Comment 4 for bug 912861

apt-cacher-ng is already a Suggests of juju. Its only necessary for use in the local provider, and the error message is graceful enough that I'm comfortable with it as-is (notice that the other local-only requirements are recommends.. I dropped apt-cacher-ng to Suggests because it is not in main). Agreed that being strict about only using apt-cacher-ng is not the best plan. bug #897645 is open upstream for a more flexible way to specify the proxy to use.