This is a regression - it worked in release_stable_2012-10-13
When navigating through start -> admin -> revert manager, the page no longer contains a working form, and the plugin cannot be used as a result. This bug affects both the rc2013-03-05 candidate and the master HEAD (currently at 5721a1547938df76003c6d91ea003dc1c70abd94).
I'm using Lighttpd, and the only change in conf/dokuwiki.php is this:
$conf['userewrite'] = 1;
I'm using a copy of the dokuwiki template (updated with each git checkout) where the only change is the filename of the logo.