Comment 7 for bug 1715141

Reviewed: https://review.opendev.org/703106
Committed: https://git.openstack.org/cgit/openstack/oslo.messaging/commit/?id=fed48aea44d2d7683516cf0e9f427cd1113c2694
Submitter: Zuul
Branch: master

commit fed48aea44d2d7683516cf0e9f427cd1113c2694
Author: Hervé Beraud <email address hidden>
Date: Fri Jan 17 16:24:29 2020 +0100

    Remove the deprecated blocking executor

    The blocking executor has been deprecated in Pike and marked for removal
    in Rocky, but some user like Mistral asked us to wait before. We decided
    to remove this executor for Train or next cycle, now we are in the
    Ussuri and after some researchs on usage I think we can go ahead.

    This patch drop the deprecation warnings, related unit tests and
    set the server with the threading executor is the default executor.

    Change-Id: If07bab61ee2b148658b88be98b12f8539f274efe
    Closes-Bug: #1715141