When purging an old edit, the edit is purged as expected. OK
When purging the current edit, the article rolls back as expected, but the text is garbled. FAILED
When purging the new moderated edit, the edit is purged as expected and the 'edit is awaiting approval' message disappeared. OK
When purging a previously unapproved edit, the edit is purged as expected. OK
I will need more information in order to duplicate the exact scenario you have encountered.