Fix relative links in Markdown wiki when displayed in "Project" tab

Refers to #23806.

CHANGELOG.md

@@ -43,6 +43,7 @@ Please view this file on the master branch, on stable branches it's out of date.
 
 ## 8.13.3
 
+- Fix relative links in Markdown wiki when displayed in "Project" tab !7218
 - Reduce the overhead to calculate number of open/closed issues and merge requests within the group or project
 
 ## 8.13.2 (2016-10-31)

app/controllers/projects_controller.rb

@@ -289,7 +289,8 @@ class ProjectsController < Projects::ApplicationController
       render 'projects/empty' if @project.empty_repo?
     else
       if @project.wiki_enabled?
-        @wiki_home = @project.wiki.find_page('home', params[:version_id])
+        @project_wiki = @project.wiki
+        @wiki_home = @project_wiki.find_page('home', params[:version_id])
       elsif @project.feature_available?(:issues, current_user)
         @issues = issues_collection
         @issues = @issues.page(params[:page])

spec/features/projects/wiki/user_views_wiki_in_project_page_spec.rb

+require 'spec_helper'
+
+describe 'Projects > Wiki > User views wiki in project page', feature: true do
+  let(:user) { create(:user) }
+  let(:project) { create(:empty_project) }
+
+  before do
+    project.team << [user, :master]
+    login_as(user)
+  end
+
+  context 'when repository is disabled for project' do
+    before do
+      project.project_feature.update!(
+        repository_access_level: ProjectFeature::DISABLED,
+        merge_requests_access_level: ProjectFeature::DISABLED,
+        builds_access_level: ProjectFeature::DISABLED
+      )
+    end
+
+    context 'when wiki homepage contains a link' do
+      before do
+        WikiPages::CreateService.new(
+          project,
+          user,
+          title: 'home',
+          content: '[some link](other-page)'
+        ).execute
+      end
+
+      it 'displays the correct URL for the link' do
+        visit namespace_project_path(project.namespace, project)
+        expect(page).to have_link(
+          'some link',
+          href: namespace_project_wiki_path(
+            project.namespace,
+            project,
+            'other-page'
+          )
+        )
+      end
+    end
+  end
+end