Extend the new URL-style connection string format to restrict name lookup to only IPv4 or IPv6 addresses:

  connect 'inet://server.example.org/test';
  connect 'inet4://server.example.org/test';
  connect 'inet6://server.example.org/test';

First example tries all addresses, second only IPv4 ones, third only IPv6ones. This can be used to avoid connection delays on systems where name lookup returns IPv6 addresses for some host names but attempts to connect to them time out rather than failing immediatelly (as reported, this can happen even for name "localhost" on some systems).