Broken master: 6 failures in MergeRequests::PushOptionsHandlerService

https://gitlab.com/gitlab-org/gitlab-ce/-/jobs/193583871:

Failures:

  1) MergeRequests::PushOptionsHandlerService `create` push option with a new branch behaves like a service that can create a merge request assigns the MR to the user
     Failure/Error: expect(last_mr.assignee).to eq(user)

       expected: #<User id:166 @user166>
            got: nil

       (compared using ==)
     Shared Example Group: "a service that can create a merge request" called from ./spec/services/merge_requests/push_options_handler_service_spec.rb:115
     # ./spec/services/merge_requests/push_options_handler_service_spec.rb:41:in `block (3 levels) in <top (required)>'

  2) MergeRequests::PushOptionsHandlerService `create` push option with an existing branch but no open MR behaves like a service that can create a merge request assigns the MR to the user
     Failure/Error: expect(last_mr.assignee).to eq(user)

       expected: #<User id:178 @user178>
            got: nil

       (compared using ==)
     Shared Example Group: "a service that can create a merge request" called from ./spec/services/merge_requests/push_options_handler_service_spec.rb:121
     # ./spec/services/merge_requests/push_options_handler_service_spec.rb:41:in `block (3 levels) in <top (required)>'

  3) MergeRequests::PushOptionsHandlerService `merge_when_pipeline_succeeds` push option with a new branch when coupled with the `create` push option behaves like a service that can create a merge request assigns the MR to the user
     Failure/Error: expect(last_mr.assignee).to eq(user)

       expected: #<User id:204 @user204>
            got: nil

       (compared using ==)
     Shared Example Group: "a service that can create a merge request" called from ./spec/services/merge_requests/push_options_handler_service_spec.rb:163
     # ./spec/services/merge_requests/push_options_handler_service_spec.rb:41:in `block (3 levels) in <top (required)>'

  4) MergeRequests::PushOptionsHandlerService `merge_when_pipeline_succeeds` push option with an existing branch but no open MR when coupled with the `create` push option behaves like a service that can create a merge request assigns the MR to the user
     Failure/Error: expect(last_mr.assignee).to eq(user)

       expected: #<User id:224 @user224>
            got: nil

       (compared using ==)
     Shared Example Group: "a service that can create a merge request" called from ./spec/services/merge_requests/push_options_handler_service_spec.rb:184
     # ./spec/services/merge_requests/push_options_handler_service_spec.rb:41:in `block (3 levels) in <top (required)>'

  5) MergeRequests::PushOptionsHandlerService `target` push option with a new branch when coupled with the `create` push option behaves like a service that can create a merge request assigns the MR to the user
     Failure/Error: expect(last_mr.assignee).to eq(user)

       expected: #<User id:258 @user258>
            got: nil

       (compared using ==)
     Shared Example Group: "a service that can create a merge request" called from ./spec/services/merge_requests/push_options_handler_service_spec.rb:229
     # ./spec/services/merge_requests/push_options_handler_service_spec.rb:41:in `block (3 levels) in <top (required)>'

  6) MergeRequests::PushOptionsHandlerService `target` push option with an existing branch but no open MR when coupled with the `create` push option behaves like a service that can create a merge request assigns the MR to the user
     Failure/Error: expect(last_mr.assignee).to eq(user)

       expected: #<User id:276 @user276>
            got: nil

       (compared using ==)
     Shared Example Group: "a service that can create a merge request" called from ./spec/services/merge_requests/push_options_handler_service_spec.rb:250
     # ./spec/services/merge_requests/push_options_handler_service_spec.rb:41:in `block (3 levels) in <top (required)>'

Finished in 16 minutes 14 seconds (files took 15.79 seconds to load)
971 examples, 6 failures, 1 pending

Failed examples:

rspec './spec/services/merge_requests/push_options_handler_service_spec.rb[1:1:1:1:3]' # MergeRequests::PushOptionsHandlerService `create` push option with a new branch behaves like a service that can create a merge request assigns the MR to the user
rspec './spec/services/merge_requests/push_options_handler_service_spec.rb[1:1:2:1:3]' # MergeRequests::PushOptionsHandlerService `create` push option with an existing branch but no open MR behaves like a service that can create a merge request assigns the MR to the user
rspec './spec/services/merge_requests/push_options_handler_service_spec.rb[1:2:1:3:1:3]' # MergeRequests::PushOptionsHandlerService `merge_when_pipeline_succeeds` push option with a new branch when coupled with the `create` push option behaves like a service that can create a merge request assigns the MR to the user
rspec './spec/services/merge_requests/push_options_handler_service_spec.rb[1:2:2:3:1:3]' # MergeRequests::PushOptionsHandlerService `merge_when_pipeline_succeeds` push option with an existing branch but no open MR when coupled with the `create` push option behaves like a service that can create a merge request assigns the MR to the user
rspec './spec/services/merge_requests/push_options_handler_service_spec.rb[1:3:1:3:1:3]' # MergeRequests::PushOptionsHandlerService `target` push option with a new branch when coupled with the `create` push option behaves like a service that can create a merge request assigns the MR to the user
rspec './spec/services/merge_requests/push_options_handler_service_spec.rb[1:3:2:3:1:3]' # MergeRequests::PushOptionsHandlerService `target` push option with an existing branch but no open MR when coupled with the `create` push option behaves like a service that can create a merge request assigns the MR to the user

It's only this test failing:

it 'assigns the MR to the user' do
  service.execute

  expect(last_mr.assignee).to eq(user)
end