If we put it in 2.2.x, then a reference to the issue will suffice.

All this feature does is make sure that all connections are closed in finally blocks, it's a bug to do anything otherwise.  If your code has such a bug, then what you've lost is a lifeline, not a feature.  I don't think it's necessary to document that in a migration guide from 2.2.x and 2.3.x, it's a small enough thing that the issue tracker should suffice.