make include_recipe "::foo" use current cookbook

The following code is brittle if you want to fork the cookbook and rename it
(which is a best practice when forking cookbooks for internal use):

```ruby
if node[:platform_family] == "rhel"
  include_recipe "mycookbook::_rhel"
end
```

In order for cookbooks to be easily renamable they can currently use the
syntax `include_recipe "#{cookbook_name}::_rhel"` which is unwieldy.
This patch adds `include_recipe "::_rhel"` as syntax sugar to make this
easier.

1 files changed, 5 insertions, 0 deletions

diff --git a/spec/unit/run_context_spec.rb b/spec/unit/run_context_spec.rb
index ba4f2ede68..d656111a7d 100644
--- a/spec/unit/run_context_spec.rb
+++ b/spec/unit/run_context_spec.rb
@@ -104,6 +104,11 @@ describe Chef::RunContext do
       end.to raise_error(Chef::Exceptions::CookbookNotFound)
     end
 
+    it "raises an error on a recipe with a leading :: with no current_cookbook" do
+      expect do
+        run_context.include_recipe("::aliens")
+      end.to raise_error(RuntimeError)
+    end
   end
 
   describe "querying the contents of cookbooks" do