Currently it will do full dependency resolution, but then only build a binary package without installing the packages.
This obviously doesn't work if some built-time dependencies aren't installed.
What it should do is to:
* install needed built-time dependencies
* build binary packages for all built packages, except those matched by --buildpkg-exclude
* warn the user if some packages will be installed
* not build packages at all that neither get a binary created nor get installed as built-time deps
Sounds good to me.