It would be helpful for virt-manager and virt-install development if the libvirt test driver support Attach/Detach/Update* APIs. Also, blacklisting some device type to fail hotplug/hotunplug so apps can test that failure scenario as well, maybe something inconsequential like <input> devices.
Thank you for reporting this issue to the libvirt project. Unfortunately we have been unable to resolve this issue due to insufficient maintainer capacity and it will now be closed. This is not a reflection on the possible validity of the issue, merely the lack of resources to investigate and address it, for which we apologise. If you none the less feel the issue is still important, you may choose to report it again at the new project issue tracker https://gitlab.com/libvirt/libvirt/-/issues The project also welcomes contribution from anyone who believes they can provide a solution.