Allow for deep directory path for view templates.

actionpack/lib/action_view/digestor.rb

@@ -64,7 +64,7 @@ module ActionView
       end
 
       def directory
-        name.split("/").first
+        name.split("/")[0..-2].join("/")
       end
 
       def partial?

actionpack/test/fixtures/digestor/level/below/index.html.erb

@@ -0,0 +1 @@
+<%= render partial: "header" %>

actionpack/test/template/digestor_test.rb

@@ -59,6 +59,12 @@ class TemplateDigestorTest < ActionView::TestCase
       change_template("comments/_comment")
     end
   end
+  
+  def test_directory_depth_dependency
+    assert_digest_difference("level/below/index") do
+      change_template("level/below/_header")
+    end
+  end
 
   def test_logging_of_missing_template
     assert_logged "Couldn't find template for digesting: messages/something_missing.html" do