Comment 60 for bug 260492

Here is what needs to be done:
 - have a new key (need_fixup or somthing) defaulting to false
 - a postinst snippet setting it to true for upgrades
 - gnome-panel code which reads this key and call the code when the key is true
 - the code change the default association to nautilus if that's not nautilus yet
 - and after running the key is set to false