Skip relative links render in help page.

features/project/source/markdown_render.feature

@@ -68,3 +68,8 @@ Feature: Project markdown render
     When I go back to wiki page home
     And I click on Rake tasks link
     Then I see Rake tasks directory
+
+  Scenario: I visit the help page with markdown
+    Given I visit to the help page
+    And I select a page with markdown
+    Then I should see a help page with markdown

features/steps/project/project_markdown_render.rb

@@ -150,4 +150,16 @@ class Spinach::Features::ProjectMarkdownRender < Spinach::FeatureSteps
     page.should have_content "backup_restore.md"
     page.should have_content "maintenance.md"
   end
+
+  Given 'I visit to the help page' do
+    visit help_path
+  end
+
+  And 'I select a page with markdown' do
+    click_link "Rake Tasks"
+  end
+
+  Then 'I should see a help page with markdown' do
+    page.should have_content "GitLab provides some specific rake tasks to enable special features or perform maintenance tasks"
+  end
 end 

lib/redcarpet/render/gitlab_html.rb

@@ -35,7 +35,11 @@ class Redcarpet::Render::GitlabHTML < Redcarpet::Render::HTML
   end
 
   def preprocess(full_document)
-    h.create_relative_links(full_document, @project.path_with_namespace, @ref, @request_path, is_wiki?)
+    if @project
+      h.create_relative_links(full_document, @project.path_with_namespace, @ref, @request_path, is_wiki?)
+    else
+      full_document
+    end
   end
 
   def postprocess(full_document)