While debugging issues related to a self-signed certificate, I came across the Certificate Manager pop-up. This can be accessed in the Settings, under Privacy & Security, by clicking on the Manage Certificates button.

The Servers tab had a button for 'Add Exception'. I tried to add an exception, but it wasn't clear how this is supposed to work. I tried entering a location in form that is shown by existing exceptions and clicking on the Get Certificate button, but this resulted in a response of "No Information Available ... Unable to obtain identification status for this site." Is there any documentation or hints on how this is supposed to work?