Merge branch 'unify-parallel_importer' into 'master'

Bring changes from EE for parallel_importer.rb

See merge request gitlab-org/gitlab-ce!19779

lib/gitlab/github_import/parallel_importer.rb

@@ -15,6 +15,15 @@ module Gitlab
         true
       end
 
+      # This is a workaround for a Ruby 2.3.7 bug. rspec-mocks cannot restore
+      # the visibility of prepended modules. See
+      # https://github.com/rspec/rspec-mocks/issues/1231 for more details.
+      if Rails.env.test?
+        def self.requires_ci_cd_setup?
+          raise NotImplementedError
+        end
+      end
+
       def initialize(project)
         @project = project
       end