Make sure all of these move to the root of the repository first, then
return to where they were afterwards, using pushd/popd. This allows them
to be executed from anywhere in the repo.
1. Only build on GitLab when there's a tag.
2. Add the packages on GitLab to component "pvc" in the repo.
3. Add build-unstable-deb.sh script to build git-versioned packages.
4. Revamp build-and-deploy to use build-unstable-deb.sh and cut down on
output.