Cannot rename tags for hidden documents from the Main.Tags page

Steps to reproduce:

• Add a tag "test rename" on a hidden page (e.g. XWiki.WebHome)
• Click on the tag to display all documents using it
• Click on Rename and add a new name "test rename2"
• Click Rename
  Result:
• The following error appears:

  Renaming of tag test rename to test rename2 failed.