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

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

coverage2sql is ready with python 3 and ok to drop the
python 2.7 support.

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

Change-Id: I7e523bff1144d827dd1377c00d4a51512e265a85

.zuul.yaml

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

doc/requirements.txt

@@ -3,6 +3,5 @@
 # process, which may cause wedges in the gate later.
 openstackdocstheme>=1.20.0 # Apache-2.0
 reno>=2.5.0 # Apache-2.0
-sphinx!=1.6.6,!=1.6.7,>=1.6.2,<2.0.0;python_version=='2.7' # BSD
-sphinx!=1.6.6,!=1.6.7,!=2.1.0,>=1.6.2;python_version>='3.4' # BSD
+sphinx!=1.6.6,!=1.6.7,!=2.1.0,>=1.6.2 # BSD
 sphinxcontrib-svg2pdfconverter>=0.1.0 # BSD

releasenotes/notes/drop-py-2-7-d2d687be179edc03.yaml

@@ -0,0 +1,6 @@
+---
+upgrade:
+  - |
+    Python 2.7 support has been dropped. Last release of coverage2sql
+    to support py2.7 is OpenStack Train. The minimum version of Python now
+    supported by coverage2sql 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/coverage2sql/latest/
+python-requires = >=3.6
 classifier =
     Environment :: OpenStack
     Intended Audience :: Information Technology
@@ -13,8 +14,6 @@ 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

tox.ini

@@ -1,9 +1,11 @@
 [tox]
-minversion = 2.0
-envlist = py{37,36,27},pep8,pip-check-reqs
+minversion = 3.1.1
+envlist = py{37,36},pep8,pip-check-reqs
 skipsdist = True
+ignore_basepython_conflict = True
 
 [testenv]
+basepython = python3
 usedevelop = True
 install_command = pip install -U --force-reinstall {opts} {packages}
 setenv = VIRTUAL_ENV={envdir}
@@ -15,17 +17,14 @@ commands =
     stestr run {posargs}
 
 [testenv:pep8]
-basepython = python3
 sitepackages = False
 commands =
     flake8 {posargs}
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:cover]
-basepython = python3
 setenv =
     {[testenv]setenv}
     PYTHON=coverage run --source coverage2sql --parallel-mode
@@ -40,7 +39,6 @@ commands =
 
 
 [testenv:docs]
-basepython = python3
 deps =
   -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
   -r{toxinidir}/requirements.txt
@@ -48,7 +46,6 @@ deps =
 commands = sphinx-build -W -b html doc/source doc/build/html
 
 [testenv:pdf-docs]
-basepython = python3
 deps = {[testenv:docs]deps}
 whitelist_externals =
    make
@@ -57,11 +54,9 @@ commands =
    make -C doc/build/pdf
 
 [testenv:debug]
-basepython = python3
 commands = oslo_debug_helper {posargs}
 
 [testenv:releasenotes]
-basepython = python3
 deps =
   -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
   -r{toxinidir}/requirements.txt
@@ -81,7 +76,6 @@ exclude=.venv,.git,.tox,dist,doc,*lib/python*,*egg,build,releasenotes
 
 
 [testenv:pip-check-reqs]
-basepython = python3
 # Do not install test-requirements as that will pollute the virtualenv for
 # determining missing packages.
 # This also means that pip-check-reqs must be installed separately, outside
@@ -93,7 +87,6 @@ commands=
     pip-missing-reqs -d --ignore-file=coverage2sql/tests/* coverage2sql
 
 [testenv:bindep]
-basepython = python3
 # Do not install any requirements. We want this to be fast and work even if
 # system dependencies are missing, since it's used to tell you what system
 # dependencies are missing! This also means that bindep must be installed