Subject: Make .unpersist() non-blocking by default?

Seems to make sense to have it false by default.

(I agree this deserves a dev list mention though even if there is easy
consensus). We should make sure we mark the Jira with releasenotes so we
can add it to uograde guide.

On Mon, Jan 28, 2019 at 8:47 AM Sean Owen <[EMAIL PROTECTED]> wrote: