I'm closing this *without* converting ContextDecorator._recreate_cm() to a public method (although I'm also attaching the patch that would have done exactly that).

My rationale for doing so is that I *still* consider making _GeneratorContextManager a subclass of ContextDecorator a design error on my part. Converting the existing _recreate_cm() hook to a public refesh_cm() method would be actively endorsing that mistake and encouraging others to repeat it.

If anyone else wants to pursue this, create a new issue and be prepared to be very persuasive. After all, the current module maintainer just rejected his own implementation of the feature :)