Steps to reproduce:
1. Create 2 pages (page1 and page2), with one of them having a child page.
2. Edit the child page, and change the parent from the original to the 2nd page.
The version 1.0 and version 1.1 of the child page have the same parent, page2
The version 1.0 and version 1.1 of the child page don't have the same parent. version 1.0 -> page1 and version 1.1 -> page2