Retag is dead, long live retag.
Erm. Long live smarter edit.
Retag is gone. It has ceased to be. The "please go back and click the retag link instead of edit" message is gone. We will (not) miss it.
Editing tags only will result in the same behavior as retag, except for the message (low enough rep will put it in review queue for suggested edits, having the retag questionsretag questions privilege will make it a regular edit.