Re-introduce refactored AptCache to wrap apt-cache usage. Use it in read-only mode for working with the host cache for use with build-packages, and use it to create a new transient cache for use with handling stage packages. It will symlink the host /etc/apt configuration so it matches the host configuration, but allow for an empty cache to mark packages and dependencies for fetching. The strategy of marking stage packages ourselves was more complicated than it appeared, and this achieves a far better result with less risk of affecting existing snaps. Additionally this fixes primed-stage-packages, which mistakenly was using a `:` instead of `=` to split the name and version. TODO: unit tests and a spread test for the manifest Signed-off-by: Chris Patterson <chris.patterson@canonical.com> - [ ] Have you followed the [guidelines for contributing](https://github.com/snapcore/snapcraft/blob/master/CONTRIBUTING.md)? - [ ] Have you signed the [CLA](http://www.ubuntu.com/legal/contributors/)? - [ ] Have you successfully run `./runtests.sh static`? - [ ] Have you successfully run `./runtests.sh tests/unit`? -----