Comment 5 for bug 1504053

Reviewed: https://review.openstack.org/232265
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=8f58bbf38f5984e70d6e0be7427deb99d7782d1d
Submitter: Jenkins
Branch: master

commit 8f58bbf38f5984e70d6e0be7427deb99d7782d1d
Author: Kevin Benton <email address hidden>
Date: Tue Oct 6 20:16:15 2015 -0700

    Fixed multiple py34 gate issues

    1. Scope mock of 'open' to module

    By mocking 'open' at the module level, we can avoid affecting
    'open' calls from other modules.

    2. Stop using LOG.exception in contexts with no sys.exc_info set

    Python 3.4 logger fills in record.exc_info with sys.exc_info() result
    [1], and then it uses it to determine the current exception [2] to
    append to the log message. Since there is no exception, exc_info[1] is
    None, and we get AttributeError inside traceback module.

    It's actually a bug in Python interpreter that it attempt to access the
    attribute when there is no exception. It turns out that it's fixed in
    latest master of cPython [3] (the intent of the patch does not seem
    relevant, but it removes the offending code while reshuffling the code).
    Note that now cPython correctly checks the exception value before
    accessing its attributes [4].

    The patch in cPython that resulted in the failure is [5] and is present
    since initial Python 3k releases.

    The patch in fixtures that broke us is [6].

    [1]: https://hg.python.org/cpython/file/tip/Lib/logging/__init__.py#l1412
    [2]: https://hg.python.org/cpython/file/tip/Lib/logging/__init__.py#l575
    [3]: https://hg.python.org/cpython/rev/73afda5a4e4c
    [4]: https://hg.python.org/cpython/rev/73afda5a4e4c#l6.484
    [5]: https://hg.python.org/cpython/rev/2ee09afee126
    [6]: https://github.com/testing-cabal/fixtures/commit/67dd2956943261e845a866dab155208c51da937e

    Closes-Bug: #1503847
    Closes-Bug: #1504053
    Co-Authored-By: Ihar Hrachyshka <email address hidden>
    Change-Id: I456b7846b8a53e4d3f8c91583685e0e1eaa84719