How can you programmatically get a Python package's list of dependencies?

The standard `setup.py` has these documented, but I can't find an easy way to access it *from* either Python or the command line.

Ideally, I'm looking for something like:

```
$ pip install somepackage --only-list-deps
kombu>=3.0.8
billiard>=3.3.0.13
boto>=2.26

```

or:

```
>>> import package_deps
>>> package = package_deps.find('somepackage')
>>> print package.dependencies
['kombu>=3.0.8', 'billiard>=3.3.0.13', 'boto>=2.26']

```

Note, I'm not talking about importing a package and finding all referenced modules. While this might find most of the dependent packages, it wouldn't be able to find the minimum version number required. That's only stored in the setup.py.