Redmine

In Redmine (at least as of 1.3.3) I can roll back to a previous version of a wiki page, which creates a new version that undoes a wiki edit. But the previous version is still visible in the history. I'd like to be able to delete a recent version so that it's completely gone from the history. This would be useful because when spammers attack our wiki site, I want to delete their changes completely to be sure that no spam links will ever be seen by a web crawler. Today, I have to delete and recreate each wiki page entirely (destroying its history) when it suffers a spam attack.