> But, more importantly, this is a new feature so it doesn't break any existing code.

I imagine you're almost done with the beta-1 release, Ned, so I'd hate to create more work for you here.  Let's release beta-1 as is.

> and in that time we need to decide what the proper actions for 3.7 (fix, reimplement, remove) and for 3.8.

I have a different opinion on this though.  The committed PR is **fundamentally** broken (releases GIL for Python code, refleaks, SIGABRT, nonsensical test) and the feature itself is very questionable.  As soon as 3.7 branch appears, I'll revert the commit from 3.7 and from master.

If we want this feature to be kept in 3.7beta2, someone should write a **new** patch from scratch.  But I strongly suggest to first discuss it on python-dev, because as is, not only the commit is broken, the proposed API is broken too from my standpoint.