Upon extension upgrade, pages might end up in "Delete unused wiki pages" for no good reason

Steps to reproduce :

• Create 3 extensions : A, B and C
  • A will be the extension that we will install
  • B and C are direct dependencies of A, B is a dependency declared before C in the pom.xml of A
  • B and C are two XAR packages :
    • B provides the pages "CommonPage" and "BPage"
    • C provides the pages "CommonPage" and "CPage"
• Install A on a wiki, make sure that the 3 pages are present and correctly installed in the wiki. As C was declared after B in the pom.xml of A, the "CommonPage" should be the one declared in C, and not in B.
• Create a new version of A, B and C with no major changes, except that B does not provide "CommonPage" anymore (the page is now only provided by C).
• Upgrade A on the wiki

Expected : The three pages stay as-is in the wiki, no particular question is asked to the user upon upgrade

Actual : The upgrade shows a question "Delete unused wiki pages ?" asking to delete "CommonPage"

This page is actually still used by C, the reason why it shows up here is because it has been deleted in a new version of B, however, as there is still one extension that provides this page, it should not appear in this question.

This is especially true as C has precedence over B in the pom.xml of A.