Software Updater should prompt for release upgrade after installing all updates; should warn of new release available even before

What does the following command run in a terminal return?

/usr/lib/ubuntu-release-upgrader/check-new-release

$ /usr/lib/ubuntu-release-upgrader/check-new-release
Checking for a new Ubuntu release
New release '13.04' available.
Run 'do-release-upgrade' to upgrade to it.

Actually, I think the same thing is happening with upgrades from R to S and the message regarding a new version of Ubuntu never appears in update-manager.

I can't reproduce this bug on either 12.10 or 13.04. (in both cases, I get prompted to upgrade)

You are up-to-date otherwise right? It won't prompt you if you have updates available.

Hey, I have run it manually now and it worked! It says "Your software is up to date. However, there is (...) 13.04 available" and leave me upgrade.

So the key must be here:
> You are up-to-date otherwise right? It won't prompt you if you have updates available.

In past releases, when I upgraded e.g. from 11.10 to 12.04, or from 10.10 to 11.04, I didn't have to manually run Software Updater. It would pop up automatically when updates where available, and I'm almost sure it DID prompt to upgrade even if there were updates available. IF not, then it showed it after installing available updates for the current release. I never have to do it manually, as in "let's run Software Updater to see whether the next major release is available". I always saw it when it automatically popped up, as in "Oh, look! There is also a new major release available!".
And that's how it should work.
It makes sense that it does, but then, AFTER installing the available updates, it should prompt for upgrading.

I mean, during all these weeks I saw the Software Updater pop up automatically hundreds of time, and I always installed all the available updates, and it never prompted me for upgrade, because there were always updates available when it popped up (other wise it wouldn't pop up in the first place). That's stupid, I kept waiting for all this month thinking "hey, 13.04 should be out already, or they'll have to call it 13.05". It never occurred to me that if I ran it manually anything would change.

[Expired for update-manager (Ubuntu) because there has been no activity for 60 days.]

I don't think it should warn of new release before updating. I think it's best to get all updates first, in case we SRU something to fix the upgrade experience. But sure, we could tell the user after updating.