title: "must be member of role" error raises when try to set one user access to another user objects
body: <p>On google cloud, with &quot;postgres&quot; user (which is not superuser), i do:</p>
  <pre><code>CREATE ROLE postgres_subuser1 LOGIN PASSWORD 'some_pass';
  CREATE ROLE postgres_subuser2 LOGIN PASSWORD 'some_pass';
  
  GRANT postgres TO postgres_subuser1;
  GRANT postgres TO postgres_subuser2;
  </code></pre>
  <p>Above part wroks, though then I try to set users access on each other objects:</p>
  <pre><code>ALTER DEFAULT PRIVILEGES FOR ROLE postgres_subuser1 GRANT ALL PRIVILEGES ON TABLES TO postgres_subuser2; 
  ALTER DEFAULT PRIVILEGES FOR ROLE postgres_subuser2 GRANT ALL PRIVILEGES ON TABLES TO postgres_subuser1;
  </code></pre>
  <p>gives: <code>must be member of role &quot;postgres_subuser1&quot;</code></p>
  <p>How can solve that?</p>
  <p>BTW, if try same on local instance, it works without any error, but this error raises on google cloud.</p>