Merge branch 'fix-rubocop' into 'master'

Remove offending empty line to make rubocop happy

see https://gitlab.com/gitlab-org/gitlab-ce/builds/2931496

See merge request !5732

spec/services/merge_requests/merge_request_diff_cache_service_spec.rb

 require 'spec_helper'
 
 describe MergeRequests::MergeRequestDiffCacheService do
-
   let(:subject) { MergeRequests::MergeRequestDiffCacheService.new }
 
   describe '#execute' do