This causes non-local side effects that are hard to track down. E.g:

--- import errors ---
Failed to import test module: tests.test_merge_yaml
Traceback (most recent call last):
  File "/home/will/.pyenv/versions/3.7.7/lib/python3.7/unittest/loader.py", line 436, in _find_test_path
    module = self._get_module_from_name(name)
  File "/home/will/.pyenv/versions/3.7.7/lib/python3.7/unittest/loader.py", line 377, in _get_module_from_name
    __import__(name)
  File "/home/will/code/kolla-ansible/tests/test_merge_yaml.py", line 19, in <module>
    from ansible.errors import AnsibleModuleError
ModuleNotFoundError: No module named 'ansible.errors'; 'ansible' is not a package

This `'ansible' is not a package` message occurs because ansible is a Mock.

Depends-On: https://review.opendev.org/#/c/726768/
Change-Id: Iddbdd3d855daadbf12536cc990559e6b8e123051

Removes and/or replaces all mentions of py27.

Cleans up obsolete requirements and their lower-constraints.

Separates test-requirements.

Makes lower-constraints pass outside of CI (MarkupSafe).

Adds FIXMEs about some hacky Mocks that may misbehave.

Change-Id: Ifc090bf3c1db17d8542ee591c91e8225a597bfe2

Now that py2 is gone, oslotest dropped dependency on mock and will
soon affect Ussuri CI [1], let's use unittest.mock built in py3.

This also fixes py38 jobs and proactively prevents py36 and py37
failing due to [1]. This is because we never included mock in
test-requirements (but in lower-constraints where it does not
really belong at all) and instead relied on oslotest to bring
it in.

[1] https://review.opendev.org/716322

Change-Id: I30e82e2d87418272a71c7ee089a8acdaf8872158

These are executed on the local host where we run ansible-playbook,
and we have agreed to drop Python 2 support there.

Partially Implements: blueprint drop-py2-support
Change-Id: Id2190c3a22a56f4f048afbf0f7200daa8f41a292

Services such as Zookeeper and Kafka use ini files which do not
explicitly specify sections. This change supports merging ini
files with no sections, so that the configuration for these
services follows the example configuration provided for them
as closely as possible.

Closes-Bug: #1756101
Partially-Implements: blueprint monasca-roles
Change-Id: I1061729875e5545c7af7d80779f9c2124b6c7134

There is inconsistent use of either `/usr/bin/python` or
`/usr/bin/env python`. This makes for unexpected results when a
user might be using a virtualenv.

Change-Id: Ibb030f920a8869f9113ade70b66a921cc815060d

Change-Id: I7df581243deef7bda4b9b5926addf61421bd42f7

Change-Id: Ibf9ee55c48a5181c5ba3aa46bef485cd3468f14c
Closes-Bug: #1647065