This use was always considered incorrect and was fixed per bug 19006.

No, the prior behavior was to show the name of the current user loading the page. However, the current behavior is to show nothing. If the point of the revision functions is to show information about the last saved revision, then neither behavior is correct.

I'm not looking for a {{CURRENTUSER}}. I'm just looking for revision magic words that actually report information about the saved revision.

You are right- it should not show nothing.

Note that the behaviour of {{REVISIONID}} and {{REVISIONUSER}} in an edit page
preview IS to return blank. It seams the behaviour has just changed to use the
behaviour of an edit page preview (since you are on the edit page) rather than
the latest revision of the page or some custom behaviour.

https://secure.wikimedia.org/wikipedia/en/w/index.php?&diff=prev&oldid=454282519

This has also broken all the policy and guideline editnotices, which use {{tl|policy-guideline-editnotice}}, which uses {{tlc|REVISIONUSER}}

We very sorry this could included in 1.18, but this we decided to take care of the long-open bug to remove this feature.

tagging bugs for Marcus to look at