How to provide 4th argument for NM.SecretAgentOldGetSecretsFunc when there's no error

I’m using Network Manager (NM 1.0) from PyGObject to create a widget that can show and connect to a network. I created a subclass of NM.SecretAgentOld to provide passwords to NM, basically I just overwrite the virtual method

def do_get_secrets(
    self, 
    connection,
    connection_path,
    setting_name,
    hints,
    flags,
    callback,
    *callback_data
):
    <after retrieving the password>
    <convert password to GLib.Variant>
    callback(self, connection, password, None)

And after retrieving the password I simply call the callback provided by NM. However callback (or more specifically NM.SecretAgentOldGetSecretsFunc type) takes 4th argument as a GLib.Error in case of any error. But it doesn’t mention what to use when there’s no error and using None raises a type error. The example from the official Network Manager python example (Making sure you're not a bot!) also shows type error.

How can I fix this?

That’s a known problem, fixed in NM’s development version:

Thanks! Any idea when it’s going to get reflected in the main because the commit is like 2 months old?