5737: Merge branch 'master' into 5737-ruby231

diff --cc apps/workbench/app/controllers/application_controller.rb
Simple merge

diff --cc build/run-tests.sh
Simple merge

diff --cc services/api/Gemfile
Simple merge

diff --cc services/api/Gemfile.lock
Simple merge

diff --cc services/api/app/controllers/application_controller.rb
Simple merge

diff --cc services/api/app/models/arvados_model.rb
Simple merge

diff --cc services/api/app/models/collection.rb
Simple merge

diff --cc services/api/app/models/log.rb
Simple merge

diff --cc services/api/app/models/node.rb
index c16e59a73c1a273dffeac557f6f78d4fbbea7caf,e470e4c2bd9c47a45b395a4c90f4814edf89a417..18550204669c7cc6353d87cfc863bcbf3c4d876a
--- 1/services/api/app/models/node.rb
--- 2/services/api/app/models/node.rb
+++ b/services/api/app/models/node.rb
@@@ -226,10 -226,10 +230,10 @@@ class Node < ArvadosMode
      (0..Rails.configuration.max_compute_nodes-1).each do |slot_number|
        hostname = hostname_for_slot(slot_number)
        hostfile = File.join Rails.configuration.dns_server_conf_dir, "#{hostname}.conf"
 -      if !File.exists? hostfile
 +      if !File.exist? hostfile
          n = Node.where(:slot_number => slot_number).first
          if n.nil? or n.ip_address.nil?
-           dns_server_update(hostname, '127.40.4.0')
+           dns_server_update(hostname, UNUSED_NODE_IP)
          else
            dns_server_update(hostname, n.ip_address)
          end

diff --cc services/api/app/models/user.rb
Simple merge

diff --cc services/api/test/functional/arvados/v1/collections_controller_test.rb
Simple merge

diff --cc services/api/test/functional/arvados/v1/jobs_controller_test.rb
Simple merge