add-apt-repository -r unable to remove a PPA that no longer has a release file

[Graham Inggs]

Similar to LP: #1855681 in ppa-purge.

sudo add-apt-repository -r ppa:jonathonf/python-3.6

 This PPA has been removed from public access as part of a protest against the abuse of open-source projects by large companies. For more detail visit the main page here: https://launchpad.net/~jonathonf

If you are a company and you would like this PPA to continue then let me know your preferred route for contributions and I will arrange something.

If we have already been in contact then ping me your Launchpad ID and I will add you to a private PPA in the meantime.
More info: https://launchpad.net/~jonathonf/+archive/ubuntu/python-3.6
Press [ENTER] to continue or Ctrl-c to cancel removing it.

Pressing Enter doesn't produce an error, but it doesn't remove the PPA either.