Semver not taken in account

I'm running into an issue where berkshelf doesn't constrain itself to the metadata restrictions.

To reproduce:

    git clone git@github.com:opscode-cookbooks/nginx.git
    git checkout v2.0.4

Go in `metadata.rb`, and change to the following:

    depends 'apt',             '~> 2.2'

    OR

    depends 'apt',             '>= 2.2', '< 2.3'

Run berks and it'll grab `apt 2.3.0` no matter what.

A quick look at [apt](http://cookbooks.opscode.com/api/v1/cookbooks/apt) reveals a version `2.2.1`.

Any ideas?


PS: using Berkshelf (2.0.10)