Merge branch 'fix-cache-clear-test-issue' into 'master'

Use project repository expire_cache to clear cache in test

Clearing the entire Redis cache in 643557da for the `branches_spec.rb` may be causing issues. Just clear what we need.

See merge request !1022

spec/requests/api/branches_spec.rb

@@ -13,13 +13,9 @@ describe API::API, api: true  do
   let!(:branch_sha) { '0b4bc9a49b562e85de7cc9e834518ea6828729b9' }
 
   describe "GET /projects/:id/repository/branches" do
-    before do
-      # Ensure that repository.branch_names is cleared from the cache at start to ensure
-      # the list matches reality
-      Rails.cache.clear
-    end
-
     it "should return an array of project branches" do
+      project.repository.expire_cache
+
       get api("/projects/#{project.id}/repository/branches", user)
       expect(response.status).to eq(200)
       expect(json_response).to be_an Array