[ussuri][goal] Drop python 2.7 support and testing

OpenStack is dropping the py2.7 support in ussuri cycle.

Complete discussion & schedule can be found in
- http://lists.openstack.org/pipermail/openstack-discuss/2019-October/010142.html
- https://etherpad.openstack.org/p/drop-python2-support

Ussuri Communtiy-wide goal:
https://governance.openstack.org/tc/goals/selected/ussuri/drop-py27.html

Remove install_command from tox.ini as cleanup.
Switch to Ussuri jobs

Change-Id: I1a3b3e542f2a6cb03f98d80ec5685c315031eed7
Sem-Ver: api-break

.zuul.yaml

@@ -1,7 +1,6 @@
 - project:
     templates:
-      - openstack-python-jobs
+      - openstack-python3-ussuri-jobs
-      - openstack-python3-train-jobs
       - openstack-cover-jobs
       - publish-openstack-docs-pti
       - openstack-lower-constraints-jobs

releasenotes/notes/drop-python-2-7-73d3113c69d724d6.yaml

@@ -0,0 +1,5 @@
+---
+upgrade:
+  - |
+    Python 2.7 support has been dropped. The minimum version of Python now
+    supported by reno is Python 3.6.

setup.cfg

@@ -6,6 +6,7 @@ description-file =
 author = OpenStack
 author-email = openstack-discuss@lists.openstack.org
 home-page = https://docs.openstack.org/reno/latest/
+python-requires = >=3.6
 classifier =
     Environment :: OpenStack
     Intended Audience :: Information Technology
@@ -13,11 +14,11 @@ classifier =
     License :: OSI Approved :: Apache Software License
     Operating System :: POSIX :: Linux
     Programming Language :: Python
-    Programming Language :: Python :: 2
-    Programming Language :: Python :: 2.7
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
+    Programming Language :: Python :: 3 :: Only
+    Programming Language :: Python :: Implementation :: CPython
 
 [files]
 packages =
@@ -31,10 +32,8 @@ distutils.commands =
 
 [extras]
 sphinx =
-  sphinx>=1.6.1,!=1.6.6,!=1.6.7,<2.0.0;python_version=='2.7'  # BSD
+  sphinx>=1.6.1,!=1.6.6,!=1.6.7,!=2.1.0  # BSD
-  sphinx>=1.6.1,!=1.6.6,!=1.6.7,!=2.1.0;python_version>='3.4'  # BSD
+  docutils>=0.11  # OSI-Approved Open Source, Public Domain
-  docutils>=0.11,<0.15;python_version=='2.7'  # OSI-Approved Open Source, Public Domain
-  docutils>=0.11;python_version>='3.4'  # OSI-Approved Open Source, Public Domain
 
 [compile_catalog]
 directory = reno/locale
@@ -44,6 +43,3 @@ domain = reno
 domain = reno
 output_dir = reno/locale
 input_file = reno/locale/reno.pot
-
-[wheel]
-universal = 1

setup.py

@@ -16,14 +16,6 @@
 # THIS FILE IS MANAGED BY THE GLOBAL REQUIREMENTS REPO - DO NOT EDIT
 import setuptools
 
-# In python < 2.7.4, a lazy loading of package `pbr` will break
-# setuptools if some other modules registered functions in `atexit`.
-# solution from: http://bugs.python.org/issue15881#msg170215
-try:
-    import multiprocessing  # noqa
-except ImportError:
-    pass
-
 setuptools.setup(
     setup_requires=['pbr'],
     pbr=True)

tox.ini

@@ -1,10 +1,11 @@
 [tox]
-minversion = 2.0
+minversion = 3.1.0
-envlist = py27,py37,pep8
+envlist = py37,pep8
+ignore_basepython_conflict = True
 
 [testenv]
+basepython = python3
 usedevelop = True
-install_command = pip install -U {opts} {packages}
 setenv =
    VIRTUAL_ENV={envdir}
 deps =
@@ -14,7 +15,6 @@ commands =
     stestr run --slowest {posargs}
 
 [testenv:pep8]
-basepython = python3
 deps = {[testenv]deps}
     hacking >= 1.1.0,<1.2.0
 commands =
@@ -22,17 +22,14 @@ commands =
   reno -q lint
 
 [testenv:lower-constraints]
-basepython = python3
 deps =
   -c{toxinidir}/lower-constraints.txt
   {[testenv]deps}
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:cover]
-basepython = python3
 setenv =
    {[testenv]setenv}
    PYTHON=coverage run --source reno --parallel-mode
@@ -49,11 +46,9 @@ commands =
 deps =
   -c{toxinidir}/lower-constraints.txt
   {[testenv]deps}
-basepython = python3
 commands = sphinx-build -a -W -E -b html doc/source doc/build/html
 
 [testenv:debug]
-basepython = python3
 commands = oslo_debug_helper {posargs}
 
 [flake8]