Comment 3 for bug 1724366

Reviewed: https://review.openstack.org/512853
Committed: https://git.openstack.org/cgit/openstack/oslo.log/commit/?id=6b0b386146e48470d889e0f1b22c7a5d5798149c
Submitter: Zuul
Branch: master

commit 6b0b386146e48470d889e0f1b22c7a5d5798149c
Author: Zane Bitter <email address hidden>
Date: Mon Oct 16 16:41:44 2017 -0400

    Allow logging of unhashable exceptions in Python 3

    A bug in the Python 3 standard library,
    https://bugs.python.org/issue28603 means that calling the traceback
    module with an exception chain that includes an unhashable exception
    results in a TypeError being raised. (In Python 3, any classes that
    define __eq__() without also explicitly defining - not inheriting -
    __hash__() will be unhashable.) The TypeError itself is also part of
    such a chain, since its __context__ will be the unhashable exception. If
    we don't catch it then the thread will simply exit mysteriously, and no
    amount of logging will be able to reveal to the user what happened.

    Change-Id: I6768574f38b075c15e829df5593a45c6be66b1bc
    Closes-Bug: #1724366