Editing a page with rights in object mode will turn the group of the rights object into an absolute group reference

To reproduce:

• Create a page on a subwiki (say wiki 'a' )
• go to edit -> Acces rights from the advanced edit menu
• give edit rights to the XWikiAllGroup
• copy the page to another wiki, say wiki 'b'
• members from XWikiAllGroup of wiki b will be able to edit the page
• got back to the page on wiki 'a'
• edit in object mode (from the advanced edit menu)
• save without making any modification
• copy the page to wiki 'c'
• members of the XWikiAllGroup of the wiki c will not be able to edit the page, only members of group XWikiAllGroup on wiki a will have rights on the page.

This is a direct consequence of XWIKI-10046 and it's particularily annoying when wiki a is a template wiki, or the modified page is the page of an application that we want to install on multiple wikis but develop on wiki 'a' .