The folks in that GitHub issue or in the #configurationmgmt channel of Slack will know best about the Anisible specifics. However, as far as a general workflow goes, I would expect it to be something like this:
- Install the new certificate
- Modify the web service to use the new certificate
- Remove the old certificate
You may end up with a disconnection before you get a response to step 2, I'm not sure. You'd want to handle the error and retry in that case.