title: How to modify all databases when overriding DiscoverRunner setup_databases with parallel
body: <p>I'm running the tests with --parallel and want to add some object to every database that is created (for each process).</p>
  <p>currently, I have a CustomTestRunner which inherit from DiscoverRunner.</p>
  <p>In that class, I'm overriding setup_databases method.</p>
  <p>after calling super().setup_databases(), I'm making a change in the db (like Users.objects.create(....))</p>
  <p>The changes occur only in one of the databases, But I want that change to be in all of them.</p>
  <p>How can I achieve that?
  <a href="https://i.stack.imgur.com/ie3Jl.png" rel="nofollow noreferrer">My Custom Test Runner</a></p>