Update UPPER_CONSTRAINTS_FILE for stable/rocky

The new stable upper-constraints file is only available
after the openstack/requirements repository is branched.
This will happen around the RC1 timeframe.

Recheck and merge this change once the requirements
repository has been branched.

The CI system will work with this patch before the requirements
repository is branched because zuul configues the job to run
with a local copy of the file and defaults to the master branch.
However, accepting the patch will break the test configuration
on developers' local systems, so please wait until after the
requirements repository is branched to merge the patch.

---

Some changes are included to handle gate failures.

- Ensure python versions:
  It looks like better to specify basepython for all tox envs.
  As of the rocky release, we use python 2.7 by default.
  It is needed to make the pep8 and functional jobs.
  http://lists.openstack.org/pipermail/openstack-discuss/2019-November/010957.html

- Marking the strongswan functional test as non-voting
  As a quick look, backport commit 1dd35515d4ea7f31878cfb60612bf68e523b9e69 in
  neutron rocky introduced a new call "iptables --version". neutron-vpnaas FT
  does not configure a rootwrap filter for iptables, so it breaks the FT.
  It looks like better to fix it separately.

Co-Authored-By: Akihiro Motoki <amotoki@gmail.com>
Change-Id: I19c936b619f08280e908a00686e4bf580c840631

.zuul.yaml

@@ -8,7 +8,9 @@
       - release-notes-jobs
     check:
       jobs:
-        - neutron-vpnaas-dsvm-functional-sswan
+        # Making FT non-voting temporarily till fixed
+        - neutron-vpnaas-dsvm-functional-sswan:
+            voting: false
         - neutron-vpnaas-tempest
         - neutron-vpnaas-tox-lower-constraints
         - neutron-vpnaas-tempest-libreswan-centos
@@ -19,7 +21,8 @@
 
     gate:
       jobs:
-        - neutron-vpnaas-dsvm-functional-sswan
+        # Disable FT temporarily till fixed
+        # - neutron-vpnaas-dsvm-functional-sswan
         - neutron-vpnaas-tempest
         - neutron-vpnaas-tox-lower-constraints
     experimental:

tox.ini

@@ -10,7 +10,7 @@ setenv = VIRTUAL_ENV={envdir}
          OS_STDERR_CAPTURE={env:OS_STDERR_CAPTURE:true}
          PYTHONWARNINGS=default::DeprecationWarning
 usedevelop = True
-deps = -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt}
+deps = -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt?h=stable/rocky}
        -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 whitelist_externals = sh
@@ -20,6 +20,7 @@ commands =
 # mode. To do this define the TRACE_FAILONLY environmental variable.
 
 [testenv:functional]
+basepython = python2.7
 deps =
   {[testenv]deps}
   -r{toxinidir}/neutron_vpnaas/tests/functional/requirements.txt
@@ -50,6 +51,7 @@ whitelist_externals =
     stestr
 
 [testenv:dsvm-functional]
+basepython = python2.7
 setenv =
   OS_TEST_PATH=./neutron_vpnaas/tests/functional/openswan
   {[testenv:functional]setenv}
@@ -61,6 +63,7 @@ commands =
   stestr run {posargs}
 
 [testenv:dsvm-functional-sswan]
+basepython = python2.7
 setenv =
   OS_TEST_PATH=./neutron_vpnaas/tests/functional/strongswan
   {[testenv:functional]setenv}
@@ -72,9 +75,11 @@ commands =
   stestr run {posargs}
 
 [testenv:releasenotes]
+basepython = python2.7
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:pep8]
+basepython = python2.7
 commands =
   flake8
   pylint --rcfile=.pylintrc --output-format=colorized {posargs:neutron_vpnaas}
@@ -87,6 +92,7 @@ whitelist_externals = sh
 commands = python ./tools/check_i18n.py ./neutron-vpnaas ./tools/i18n_cfg.py
 
 [testenv:cover]
+basepython = python2.7
 setenv =
     {[testenv]setenv}
     PYTHON=coverage run --source neutron_vpnaas --parallel-mode
@@ -98,9 +104,11 @@ commands =
   coverage xml -o cover/coverage.xml
 
 [testenv:venv]
+basepython = python2.7
 commands = {posargs}
 
 [testenv:docs]
+basepython = python2.7
 commands = sphinx-build -W -a -b html doc/source doc/build
 
 [flake8]