The notification preferences of an extension defining its own events cannot be set by a subwiki user

The easiest way to reproduce this issue is the following :

• In a new, fresh instance, create a subwiki, and a user in this subwiki
• Install the blog application in this subwiki
• When logging in as the test subwiki user, notice that you cannot set your notification preferences for the blog application
• To see the expected result, install the blog application on the main wiki, and check the notification preferences of any main wiki user