Dropping lower constraints testing

We facing errors related to the new pip resolver, this
topic was discussed on the ML and QA team proposed to
to test lower-constraints [1].

I propose to drop this test because the complexity and recurring pain needed
to maintain that now exceeds the benefits provided by this mechanismes.

Replace assertTrue by assertIn to fix with the latest flake8 version.
Add six in the documentation requirements to fix the build.
Fix the conflict status with hacking.

[1] http://lists.openstack.org/pipermail/openstack-discuss/2020-December/019390.html

Change-Id: I580da15fefd6ad352e69749b77cc4664aef84f9c

.pre-commit-config.yaml

@@ -32,4 +32,4 @@ repos:
     hooks:
       - id: flake8
         additional_dependencies:
-          - hacking>=3.0.1,<3.1.0
+          - hacking==4.0.0

.zuul.yaml

@@ -110,7 +110,6 @@
       - lib-forward-testing
       - lib-forward-testing-python3
       - openstack-cover-jobs
-      - openstack-lower-constraints-jobs
       - openstack-python-jobs
       - openstack-python3-ussuri-jobs
       - periodic-stable-jobs

doc/requirements.txt

@@ -3,3 +3,4 @@ sphinx!=1.6.6,!=1.6.7,>=1.6.2;python_version>='3.4' # BSD
 sphinxcontrib-apidoc>=0.2.0  # BSD
 openstackdocstheme>=1.18.1 # Apache-2.0
 reno>=2.5.0 # Apache-2.0
+six==1.12.0 # MIT

lower-constraints.txt

@@ -1,37 +0,0 @@
-alabaster==0.7.10
-Babel==2.3.4
-docutils==0.11
-dulwich==0.15.0
-extras==1.0.0
-fixtures==3.0.0
-flake8==2.5.5
-hacking==0.12.0
-imagesize==0.7.1
-Jinja2==2.10
-linecache2==1.0.0
-MarkupSafe==1.0
-mccabe==0.2.1
-mock==2.0.0
-openstackdocstheme==1.18.1
-pep8==1.5.7
-pyflakes==0.8.1
-Pygments==2.2.0
-python-mimeparse==1.6.0
-python-subunit==1.0.0
-pytz==2013.6
-PyYAML==3.12
-reno==2.5.0
-requests==2.14.2
-six==1.12.0
-snowballstemmer==1.2.1
-Sphinx==1.6.5
-sphinxcontrib-apidoc==0.2.0
-sphinxcontrib-websupport==1.0.1
-stestr==2.1.0
-testrepository==0.0.18
-testresources==2.0.0
-testscenarios==0.4
-testtools==2.2.0
-traceback2==1.4.0
-unittest2==1.1.0
-virtualenv==20.0.3

pbr/tests/test_setup.py

@@ -218,9 +218,9 @@ class GitLogsTest(base.BaseTestCase):
 
         with open(os.path.join(self.temp_path, "AUTHORS"), "r") as auth_fh:
             authors = auth_fh.read()
-            self.assertTrue(author_old in authors)
-            self.assertTrue(author_new in authors)
-            self.assertTrue(co_author in authors)
+            self.assertIn(author_old, authors)
+            self.assertIn(author_new, authors)
+            self.assertIn(co_author, authors)
 
 
 class _SphinxConfig(object):

tox.ini

@@ -53,8 +53,3 @@ commands =
 ignore = W504
 exclude = .venv,.tox,dist,doc,*.egg,build
 show-source = true
-
-[testenv:lower-constraints]
-deps =
-  -c{toxinidir}/lower-constraints.txt
-  -r{toxinidir}/test-requirements.txt