The following 2 questions are essentially duplicates, along the lines of
'Cannot sign out of iCloud because of an old email address'
For the first, the solution was 'this is a bug that needs fixing'
For the second, it's 'there now is a solution since iOS 9.0.2'
So, the first did all the work, yet the second found the fix.
imho, both are worthy in & of themselves, but as a pair they show not only the solution, but also some back history to the problem & research done in trying to fix it.
I've already added a comment to the first to point to the newly-available solution.
They each show as 'Linked' in the right margin - though I'm not sure how many people actually use that to follow a trail of bread crumbs.
How do we better link them without 'penalising' either by marking it as a dupe? Especially as it's the newer question that has a working fix, so the 'this has already been asked & has an answer' message would give off all the wrong signals.
Add a Link in an answer - edit the original or post a new one?
Add a Link to the top of the original question "Since iOS 9.0.2 there is now a solution to this issue 'here'" ?
Any other possibility?