Add feature test for accessing MR created from fork

spec/features/merge_requests/created_from_fork_spec.rb

+require 'spec_helper'
+
+feature 'Merge request created from fork' do
+  given(:user) { create(:user) }
+  given(:project) { create(:project, :public) }
+  given(:fork_project) { create(:project, :public) }
+
+  given!(:merge_request) do
+    create(:forked_project_link, forked_to_project: fork_project,
+                                 forked_from_project: project)
+
+    create(:merge_request, source_project: fork_project,
+                           target_project: project,
+                           description: 'Test merge request')
+  end
+
+  before do
+    project.team << [user, :master]
+
+    login_as user
+    visit namespace_project_merge_request_path(project.namespace,
+                                               project, merge_request)
+  end
+
+  scenario 'user can access merge request' do
+    expect(page).to have_content 'Test merge request'
+  end
+end