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

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

sahara plugins do works with python 3 and the sahara core
does not support python 2.7 anymore anyway.

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

Also:
- bump the lower-constraints decorator requirements to a recent one
  to prevent failures;
- drop the obsolete jenkins tox target.

Change-Id: I5806dcb8f13e88a28c0b5e6de449efa9b95b6e73

.zuul.yaml

@@ -2,7 +2,6 @@
     templates:
       - openstack-cover-jobs
       - openstack-lower-constraints-jobs
-      - openstack-python-jobs
       - openstack-python3-ussuri-jobs
       - publish-openstack-docs-pti
       - check-requirements

lower-constraints.txt

@@ -7,7 +7,7 @@ cmd2==0.8.0
 coverage==4.0
 cryptography==2.1
 debtcollector==1.2.0
-decorator==3.4.0
+decorator==4.4.0
 deprecation==1.0
 dogpile.cache==0.6.2
 extras==1.0.0

releasenotes/notes/drop-py2-7-862abe2ec0c32c5f.yaml

@@ -0,0 +1,6 @@
+---
+upgrade:
+  - |
+    Python 2.7 support has been dropped. Last release of python-saharaclient
+    to support python 2.7 is OpenStack Train. The minimum version of Python now
+    supported by python-saharaclient is Python 3.6.

setup.cfg

@@ -14,8 +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 +1,13 @@
 [tox]
-envlist = py27,py37,pypy,pep8,releasenotes
-minversion = 2.0
+envlist = py37,pypy,pep8,releasenotes
+minversioon = 3.1.1
 skipsdist = True
+# this allows tox to infer the base python from the environment name
+# and override any basepython configured in this file
+ignore_basepython_conflict = true
 
 [testenv]
+basepython = python3
 usedevelop = True
 install_command = pip install {opts} {packages}
 setenv =
@@ -23,16 +27,11 @@ passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
 basepython = python3
 commands = oslo_debug_helper -t saharaclient/tests/unit {posargs}
 
-[testenv:debug-py27]
-basepython = python2.7
-commands = oslo_debug_helper -t saharaclient/tests/unit {posargs}
-
 [testenv:debug-py36]
 basepython = python3.6
 commands = oslo_debug_helper -t saharaclient/tests/unit {posargs}
 
 [testenv:cover]
-basepython = python3
 setenv =
   {[testenv]setenv}
   PYTHON=coverage run --source saharaclient --parallel-mode
@@ -45,16 +44,11 @@ commands =
   coverage xml -o cover/coverage.xml
   coverage report
 
-[tox:jenkins]
-sitepackages = False
-
 [testenv:pep8]
-basepython = python3
 sitepackages = False
 commands = flake8
 
 [testenv:doc8]
-basepython = python3
 deps =
     -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/master/upper-constraints.txt}
     -r{toxinidir}/requirements.txt
@@ -63,11 +57,9 @@ deps =
 commands = doc8 doc/source
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:docs]
-basepython = python3
 deps =
     -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/master/upper-constraints.txt}
     -r{toxinidir}/requirements.txt
@@ -77,7 +69,6 @@ commands =
   sphinx-build -W -b html doc/source doc/build/html
 
 [testenv:releasenotes]
-basepython = python3
 deps =
     -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/master/upper-constraints.txt}
     -r{toxinidir}/requirements.txt
@@ -95,7 +86,6 @@ exclude=.venv,.git,.tox,dist,doc,*lib/python*,*egg,tools
 local-check-factory = saharaclient.tests.hacking.checks.factory
 
 [testenv:lower-constraints]
-basepython = python3
 deps =
   -c{toxinidir}/lower-constraints.txt
   -r{toxinidir}/test-requirements.txt