There are two different but closely related scenarios.

1) Changing a page title

• Create Page B
• Create Page A in the same space and include a link to Page B.
  • this link will be relative (it will have no spacekey)
• Edit Page B and change the title to 'Page C'

The link in Page A will now be absolute.

2) Moving a page to the same space

• Create Page B in Space B
• Create Page A in Space A and include a link to Page B
  • this link will be absolute (it will have a spacekey)
• Move Page B to Space A

The link in Page A will wrongly be absolute to Space A (which is the space both pages are now in).