Microversions tempest tests expect no other "Vary" headers

[Goutham Pacha Ravi]

How to reproduce:

This failure was found on an RHOSP platform with TripleO deployed configuration, a gist of which is:

1) Setup a mod-wsgi proxy for the manila-api with Apache
2) Expose the manila endpoints via haproxy
3) Run manila microversion tempest tests

manila_tempest_tests.tests.api.test_microversions.MicroversionsTest.test_microversions_v1_no_version[api,positive] (from manila)

Stacktrace

Traceback (most recent call last):
testtools.testresult.real._StringException: Empty attachments:
  pythonlogging:''

Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/manila_tempest_tests/tests/api/test_microversions.py", line 71, in test_microversions_v1_no_version
    self.assertEqual(API_MICROVERSIONS_HEADER, resp.get('vary'))
  File "/usr/lib/python2.7/site-packages/testtools/testcase.py", line 350, in assertEqual
    self.assertThat(observed, matcher, message)
  File "/usr/lib/python2.7/site-packages/testtools/testcase.py", line 435, in assertThat
    raise mismatch_error
testtools.matchers._impl.MismatchError: !=:
reference = 'X-OpenStack-Manila-API-Version'
actual = 'X-OpenStack-Manila-API-Version,Accept-Encoding'

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.opendev.org/668622

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/668622
Committed: https://git.openstack.org/cgit/openstack/manila-tempest-plugin/commit/?id=0ac95412b1b0555775b4d45f51c27af2fa84724a
Submitter: Zuul
Branch: master

commit 0ac95412b1b0555775b4d45f51c27af2fa84724a
Author: lkuchlan <email address hidden>
Date: Tue Jul 2 10:11:10 2019 +0300

    Look for api microversion header in "Vary" header data

    Apache configuration adds "Accept-Encoding" to the "Vary" header
    in its responses, this causes to failures in some tests which check
    the "Vary" header content of the response.
    In order to avoid this issue we should only check that api microversion
    header axists in "Vary" header data.

    Change-Id: I1490bf8f424181233aa3ea04a8410052b385699c
    Related-bug: #1833766