How to tag an old bug to say it applies to a current release

I have been trying to work around an old bug that affects the currently supported releases of Ubuntu. There is a post at the end of the old bug thread made by "bugbot" on 2011-04-28 that says:

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This bug report was filed against an old version of Ubuntu.
Can you confirm whether this is still an issue in natty?
If you don't mind, it would be very helpful if you could update the bug
report in launchpad to 'Fix Released' if it is no longer an issue for
you, or if it is still occurring under natty, please tag the bug 'natty'
so it's easier for us to track.
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I cannot find a way to comply with the request to "tag the bug" with the name of the current release I am trying to use. How can I "tag the bug"?