All Updates feed not cleared after XML import?

[Nicolas Kreft]

I've noticed that the All Updates feed does not get cleared after restoring an XML backup from another Confluence instance as described here: https://confluence.atlassian.com/doc/restoring-a-site-152034.html

Problem with that is, that prior to the XML import,  some testpages, spaces and comments were created. These are now still visible in the All Updates feed, but lead to "page not found" error messages as those testpages do not exist in the XML dump that got restored.

Is there a way to manually clean the All Updates feed?

I have only noticed this behaviour with the All updates feed so far, but maybe there are other places that still refer to things that are non-existent anymore after the XML import? 

Or maybe it would it be better to clear the whole database prior to an XML import? How to do that?