intermittent unit test failures with TestOntologiesController#test_download_acl_only

[alexskr]

seeing an increased number of intermittent unit test failures:

 2) Error:
TestOntologiesController#test_download_acl_only:
Goo::Base::NotValidException: Object is not valid. Check errors.
    /srv/ontoportal/bundle/ruby/2.7.0/bundler/gems/goo-db2b330fb6c5/lib/goo/base/resource.rb:316:in `save'
    /srv/ontoportal/bundle/ruby/2.7.0/bundler/gems/ontologies_linked_data-e716a6d41088/lib/ontologies_linked_data/models/base.rb:13:in `save'
    /srv/ontoportal/bundle/ruby/2.7.0/bundler/gems/ontologies_linked_data-e716a6d41088/lib/ontologies_linked_data/models/users/user.rb:73:in `save'
    /srv/ontoportal/ontologies_api/test/controllers/test_ontologies_controller.rb:232:in `test_download_acl_only'

unit test failure usually resolves if test is run again