Do not add a task list

[marbetschar]

Steps to reproduce

1. Open the Nextcloud web interface
2. Navigate to the calendar
3. Create a new calendar
4. Navigate to the Tasks
5. You'll see a task list was added with the same name as the added calendar

Expected behaviour

No task list was added. Adding a calendar should not add itself as a task list.

Actual behaviour

The same calendar object seems to be shown in calendar and task modules. This leads to unexpected behaviors such as when a calendar is deleted, all tasks of it are gone too. Or if the task list is deleted, all calendar events are suddenly missing.

This issue is probably related to: nextcloud/tasks#212

Server configuration

https://cloud.linuxfabrik.io

[georgehrke]

nextcloud/server#8625