Py3.7 two tests failing with _impl.MismatchError

[Corey Bryant]

The following tests are failing for Py3.7:

======================================================================
FAIL: oslo_serialization.tests.test_jsonutils.JSONUtilsTestJson.test_dumps_exception_value
oslo_serialization.tests.test_jsonutils.JSONUtilsTestJson.test_dumps_exception_value
----------------------------------------------------------------------
_StringException: Traceback (most recent call last):
  File "/<<PKGBUILDDIR>>/oslo_serialization/tests/test_jsonutils.py", line 120, in test_dumps_exception_value
    jsonutils.dumps({"a": ValueError("hello")}))
  File "/usr/lib/python3/dist-packages/testtools/testcase.py", line 411, in assertEqual
    self.assertThat(observed, matcher, message)
  File "/usr/lib/python3/dist-packages/testtools/testcase.py", line 498, in assertThat
    raise mismatch_error
testtools.matchers._impl.MismatchError: '{"a": "ValueError(\'hello\',)"}' != '{"a": "ValueError(\'hello\')"}'

======================================================================
FAIL: oslo_serialization.tests.test_jsonutils.ToPrimitiveTestCase.test_exception
oslo_serialization.tests.test_jsonutils.ToPrimitiveTestCase.test_exception
----------------------------------------------------------------------
_StringException: Traceback (most recent call last):
  File "/<<PKGBUILDDIR>>/oslo_serialization/tests/test_jsonutils.py", line 411, in test_exception
    jsonutils.to_primitive(ValueError("an exception")))
  File "/usr/lib/python3/dist-packages/testtools/testcase.py", line 411, in assertEqual
    self.assertThat(observed, matcher, message)
  File "/usr/lib/python3/dist-packages/testtools/testcase.py", line 498, in assertThat
    raise mismatch_error
testtools.matchers._impl.MismatchError: "ValueError('an exception',)" != "ValueError('an exception')"

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/585886

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/585886
Committed: https://git.openstack.org/cgit/openstack/oslo.serialization/commit/?id=254e0ae839ecc692192f29e3aa590e6d5d3377a7
Submitter: Zuul
Branch: master

commit 254e0ae839ecc692192f29e3aa590e6d5d3377a7
Author: Corey Bryant <email address hidden>
Date: Wed Jul 25 16:52:22 2018 -0400

    py37: deal with Exception repr changes

    Under Python 3.7, a trailing comma is no longer added to
    the init parameters generated by a repr() call:

        >>> repr(Exception('It Works'))
        "Exception('It Works')"

    vs

        >>> repr(Exception('It Works'))
        "Exception('It Works',)"

    Support pre and post Python 3.7 formats in test cases.

    Change-Id: I45bdf565e170793d0342a907628638369d4d0f2f
    Closes-Bug: #1783638

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/oslo.serialization 2.28.0 release.