[COOK-1690] Compilation failure on undefined method each for nil:NilClass

Resolved issue with failure of empty each.

http://tickets.opscode.com/browse/COOK-1690

```================================================================================
Recipe Compile Error in /tmp/vagrant-chef-1/chef-solo-1/cookbooks/build-essential/recipes/default.rb
================================================================================

NoMethodError
-------------
undefined method `each' for nil:NilClass

Cookbook Trace:
---------------
/tmp/vagrant-chef-1/chef-solo-1/cookbooks/build-essential/recipes/default.rb:47:in `from_file'

Relevant File Content:
----------------------
/tmp/vagrant-chef-1/chef-solo-1/cookbooks/build-essential/recipes/default.rb:

1: #
2: # Cookbook Name:: build-essential
3: # Recipe:: default
4: #
5: # Copyright 2008-2009, Opscode, Inc.
6: #
7: # Licensed under the Apache License, Version 2.0 (the "License");
8: # you may not use this file except in compliance with the License.
9: # You may obtain a copy of the License at

[Fri, 21 Sep 2012 06:03:37 -0700] ERROR: Running exception handlers
[Fri, 21 Sep 2012 06:03:37 -0700] ERROR: Exception handlers complete
[Fri, 21 Sep 2012 06:03:37 -0700] FATAL: Stacktrace dumped to /tmp/vagrant-chef-1/chef-stacktrace.out
[Fri, 21 Sep 2012 06:03:37 -0700] FATAL: NoMethodError: undefined method `each' for nil:NilClass```