User blog comment:Rappy 4187/Technical Update: May 4, 2015/@comment-5558012-20150506160241/@comment-957747-20150506163451

As mentioned in the post (and my clarification below), the switch to enable the feature is being removed from Labs until we finalize some behind-the-scenes updates to the feature. That was a warning to those that may decide to turn off the feature in the interim.