When deleting a page that once was a parent for another page, which was moved, the moved page appears as a child in Affected Children and we get an error message once the Delete button is clicked (with a new created user)

Steps to reproduce:

1. Log in as Admin
2. Create a new user
3. Log in as that user, make it Advance user
4. Create a page e.g. x
5. Create a child page e.g. x1 (x/x1)
6. Create a child page for x1 e.g. x2 (x1/x2/)
7. Click on Move/Rename page x2
8. Click on the Pencil under New Location
9. Delete the content of the Parent field
10. Click on Rename to Move x2
11. Observe the new location of the x2 page under Navigation
12. Click on the x page
13. Click on More actions > Children (observe the children of the x page)
14. Click on Actions > Delete
15. Click on the right arrow to see the Affected children
16. Select Affect children
17. Click on Yes, please delete this page

Expected results: The x2 child page is moved as a webhome page. The x page has only x1 as a child. x doesn't appear as a child in Affect children either. The x page is deleted with the affected child x1.

Actual results: The x2 page is moved as a webhome page. In Children of x x2 doesn't appear as a child anymore (for x1). When selecting Delete under Affect children you can also see x2 as a child for x1. After clicking Yes, please delete this page there is an error, letting the user know that he is not allowed to delete x.x1.x2 - which the user didn't want to delete in the first place (x2 isn't deleted, only x and x1).