I can provide rebases if needed. And follow-ups for very explicit requested changes (I don't have the codebase knowledge to make changes from any request a bit abstract :( )

Isn't there still a benefit of having this merged? (after eventual polishing)

And no need for feature flag since currently one can save and it simply fails to restore and you are screwed. This submission can only make things better ^_^

In D4770#216573, @jpshack wrote:

It isn't clear to me what the committers believe are the most critical changes required to get this into the next release.