Make sure Cleaner doesn't remove dirs if they only contain subdirs

Closes #2204

lib/jekyll/cleaner.rb

@@ -49,7 +49,19 @@ module Jekyll
       #
       # Returns a Set with the directory paths
       def new_dirs
-        new_files.map { |file| File.dirname(file) }.to_set
+        new_files.map { |file| parent_dirs(file) }.flatten.to_set
+      end
+
+      # Private: The list of parent directories of a given file
+      #
+      # Returns an Array with the directory paths
+      def parent_dirs(file)
+        parent_dir = File.dirname(file)
+        if parent_dir == site.dest
+          return []
+        else
+          return [parent_dir] + parent_dirs(parent_dir)
+        end
       end
 
       # Private: The list of existing files that will be replaced by a directory during build

test/test_cleaner.rb

@@ -0,0 +1,38 @@
+require 'helper'
+
+class TestCleaner < Test::Unit::TestCase
+  context "directory containing no files and non-empty directories" do
+    setup do
+      clear_dest
+      stub(Jekyll).configuration do
+        Jekyll::Configuration::DEFAULTS.merge({'source' => source_dir, 'destination' => dest_dir})
+      end
+
+      FileUtils.mkdir_p(source_dir('no_files_inside/child_dir'))
+      FileUtils.touch(File.join(source_dir('no_files_inside/child_dir'), 'index.html'))
+
+      @site = Site.new(Jekyll.configuration)
+      @site.process
+
+      @cleaner = Site::Cleaner.new(@site)
+      @cleaner.cleanup!
+    end
+
+    teardown do
+      FileUtils.rm_rf(source_dir('no_files_inside'))
+      FileUtils.rm_rf(dest_dir('no_files_inside'))
+    end
+
+    should "keep the parent directory" do
+      assert File.exist?(dest_dir('no_files_inside'))
+    end
+
+    should "keep the child directory" do
+      assert File.exist?(dest_dir('no_files_inside/child_dir'))
+    end
+
+    should "keep the file" do
+      assert File.exist?(File.join(dest_dir('no_files_inside/child_dir'), 'index.html'))
+    end
+  end
+end